DOCTOR OF PHILOSOPHY IN AGRICULTURE (DEPARTMENT OF SOIL SCIENCE) (SOIL SCIENCE)

Transcription

1 PHOSPHORUS AND RAIN-HARVESTED WATER ECONOMY THROUGH VESICULAR ARBUSCULAR MYCORRHIZAE (VAM) IN OKRA-PEA SEQUENCE THESIS By ANIL KUMAR (A ) Submitted to CHAUDHARY SARWAN KUMAR HIMACHAL PRADESH KRISHI VISHVAVIDYALAYA PALAMPUR (H.P.) INDIA in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN AGRICULTURE (DEPARTMENT OF SOIL SCIENCE) (SOIL SCIENCE) 2012

2 Affectionately dedicated to revered parents Prof (Dr) V.K. Suri (Head/ OI, Agricultural Technology Information Centre) Former, Vice-Chancellor, CSAUAT, Kanpur (UP) Directorate of Extension Education CSK HPKV Palampur, HP (India)

3 CERTIFICATE I This is to certify that the thesis entitled, Phosphorus and rainharvested water economy through Vesicular Arbuscular Mycorrhizae (VAM) in okra-pea sequence, submitted in partial fulfillment of the requirements for the award of the degree of Doctor of Philosophy (Agriculture) in the subject of Soil Science to CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, is a bonafide research work carried out by Mr. ANIL KUMAR (A ), son of Sh. Sher Singh under my supervision and that no part of this thesis has been submitted for any other degree or diploma. The assistance and help received during the course of this investigation have been fully acknowledged. Place: Palampur Dated: the July 18, 2012 (V.K. Suri) Chairman, Advisory Committee

4 CERTIFICATE II This is to certify that the thesis entitled, Phosphorus and rainharvested water economy through Vesicular Arbuscular Mycorrhizae (VAM) in okra-pea sequence, submitted by Mr. ANIL KUMAR (A ), son of Sh. Sher Singh to CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Agriculture) in the subject of Soil Science, has been approved by the Advisory Committee after an oral examination of the student in collaboration with an External Examiner (Dr. V.K. Suri) External Examiner Chairman Advisory Committee (Dr. Sanjeev Sandal) Member (Dr. Kapil Saroch) Member (Dr. Vidyasagar) Member) (Dr. S. Bhan) (Dean s Nominee) Head Department of Soil Science CSK HPKV, Palampur (Dean, Postgraduate Studies)

5 ACKNOWLEDGEMENTS In this highly complex society, no work can be accomplished by a single individual but it needs inspiration and sincere gratitude of intellectuals as well as the grace of that Almighty. Emotions cannot be adequately expressed in words because then emotions are transformed into a mere formality. My acknowledgements are many times more than what I am expressing here. With unending humility, at the very outset, I would like to thank The Almighty, who blessed with the limitless internal strength and favorable circumstances, to face and pass through all odds successfully at this juncture. With an overwhelming sense of legitimate pride and genuine obligation, I seize this rare opportunity to express my deep sense of gratitude, indebtedness and personal regards to my esteemed teacher and chairman of my advisory committee, Dr. V.K. Suri (Former Vice-Chancellor, CSAUAT, Kanpur, UP, India), Professor Soil Science/ Head, Agricultural Technology Information Centre, Directorate of Extension Education, CSK HPKV, Palampur (HP)- India, for his expert, invaluable, criticism during the entire course of my investigations. I feel honoured in expressing real appreciation and regards towards Dr. K.K. Katoch (Dean, Post Graduate Studies/ Prof. and Head Deptt. of Soil Science) for their prompt anticipations, valuable suggestions and constant encouragement. I am thankful to esteemed members of my Advisory committee, Dr. Sanjeev Sandal (Scientist, Soils), Dr. Kapil Saroch (Sr. Agronomist), Dr. Vidyasagar (Prof. and Head Deptt. of Vegetable Sciences and Floriculture) and Dr. S. Bhan (Dean s nominee) for his proper guidance during the entire course of present studies. Heartily thanks are due to teachers and staff members of the Department of Soil Science, CSK HPKV, Palampur. I am grateful to Dean, P.G. Studies and staff, library staff and CSK Himachal Pradesh Krishi Vishvavidyalaya authorities for providing their full help and co-operation during the present investigation. Heartful thanks are due to Lab. Staff of Department of Soil Science, CSK HPKV Palampur (HP) for their cordial co-operation and help extended during the study, especially Sh. Ved Prakash Korla jee, Bihari lal jee, Baljeet jee, Paras Ram jee and Sh. Trilok Jee. I appreciate the whole hearted co-operation extended by my Seniors Dr. Swapana Sepehya, Dr. Shweta Shambhavi, Dr. Gayatri Verma and Dr. Susheel Dhiman for their help during the course of investigation. I expressed my heartfelt thanks to my friends Upinder, Jintu, Abhishek, Rohit, Manoj, Raj Krishan (ADC, Kullu), Ajay, Sudesh, Munish, Anil, Lokender, Prakash, Ashlesha, Arti, Renu, Shilva and Rajbir for their co-operation, encouragement, moral and timely help when demanded. I avail the blessings, affection and moral encouragement of my gracious parents, constant moral encouragement inspired me to search ahead. My deep sense of gratitude to my brother Sunil, Kiran Bhabhi jee and sister Sapna whose inspiration, love and affection always inspired me to excel in my field. I express my appreciation for all the quarters individually, which have been not mentioned here. Needless, to say, errors and ommisions are mine. Place: Palampur Dated : the July 18, 2012 (Anil Kumar) i

6 TABLE OF CONTENTS Chapter Title Page No. I. INTRODUCTION 1-4 II. REVIEW OF LITERATURE 5-24 III. MATERIALS AND METHODS IV. RESULTS AND DISCUSSION V. SUMMARY AND CONCLUSIONS LITERATURE CITED APPENDICES BRIEF BIODATA OF THE STUDENT ii

7 LIST OF ABBREVIATIONS USED Abbreviation Meaning Abbreviation Meaning % Per cent Mn Manganèse & and mm milimetre * Asterisk IW Irrigation water Ca Calcium K Potassium cm centimetre kg kilogram CPE Cumulative pan evaporation mg miligram Cu Copper Mg Magnesium DAP Di ammonium phosphate ml millilitre DAS Days after sowing mm milimetre e.g. exempli gratia (for example) N Nitrogen Fe Iron P Phosphorus FP Farmers practice ph Power of hydrogen ions g gram PSB Phosphate solubilising bacteria GRD Generalized dose PUE Phosphorus use efficiency ha Hectare RDF Recommended dose of fertilizers iii

8 Abbreviation Meaning Abbreviation Meaning i.e. id est (that is) SSP Single super phosphate INM Integrated nutrient management TSS Total soluble solids RLWC Relative leaf water content viz. videlicet (namely) RP Rock phosphate WUE Water use efficiency S Sulphur Zn Zinc sec Second iv

9 LIST OF TABLES S. No. Title 3.1 Important physical and chemical properties of experimental soil (0-15 cm) at initiation of experiment Page No Schedule of various agronomic operations in okra and pea Composition of organic manure used in experiment Analytical methods employed in soil chemical analysis Analytical methods employed in plant and manure analysis Effect of integrated application of VAM, phosphorus and irrigation on okra fruit length (cm) during crop growth 4.2 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit girth (cm) during crop growth 4.3 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit weight (g) during crop growth 4.4 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit number kg -1 during crop growth 4.5 Effect of integrated application of VAM, phosphorus and irrigation on fruit yield (q ha -1 ) of okra crop 4.6 Effect of integrated application of VAM, phosphorus and irrigation on P response ratio (kg yield kg -1 P) of okra crop 4.7 Effect of integrated application of VAM, phosphorus and irrigation on relative leaf water content (%) during okra crop growth 4.8 Effect of integrated application of VAM, phosphorus and irrigation on water use efficiency (kg ha -1 mm -1 ) of okra crop 4.9 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit quality v

10 S. No. Title 4.10 Effect of integrated application of VAM, phosphorus and irrigation on total N, P and K (kg ha -1 ) uptake by okra crop 4.11 Effect of integrated application of VAM, phosphorus and irrigation on total B and Mo uptake (g ha -1 ) by okra crop 4.12 Effect of integrated application of VAM, phosphorus and irrigation on soil ph and organic carbon status (g kg -1 ) after okra harvest 4.13 Effect of integrated application of VAM, phosphorus and irrigation on available N, P and K status (kg ha -1 ) of soil after okra harvest 4.14 Effect of integrated application of VAM, phosphorus and irrigation on exchangeable Ca and Mg status (c mol (p+) kg -1 ) of soil after okra harvest 4.15 Effect of integrated application of VAM, phosphorus and irrigation on soil available Fe, Zn, Cu and Mn status (mg kg -1 ) after okra harvest 4.16 Effect of integrated application of VAM, phosphorus and irrigation on available B and Mo status (mg kg -1 ) of soil after okra harvest Page No Economic analysis of experiment under okra Effect of integrated application of VAM, phosphorus and irrigation on pod length and girth (cm) of pea during crop growth 4.19 Effect of integrated application of VAM, phosphorus and irrigation on pod number per kg and pod weight (g) during crop growth 4.20 Effect of integrated application of VAM, phosphorus and irrigation on green pod yield (q ha -1 ) of pea 4.21 Effect of integrated application of VAM, phosphorus and irrigation on P response ratio (kg yield kg -1 P) of pea 4.22 Effect of integrated application of VAM, phosphorus and irrigation on relative leaf water content (%) during pea crop growth vi

11 S. No. Title 4.23 Effect of integrated application of VAM, phosphorus and irrigation on xylem water potential (k Pa) during pea crop growth 4.24 Effect of integrated application of VAM, phosphorus and irrigation on water use efficiency (kg ha -1 mm -1 ) of pea crop 4.25 Effect of integrated application of VAM, phosphorus and irrigation on quality of pea 4.26 Effect of integrated application of VAM, phosphorus and irrigation on total N, P and K uptake (kg ha -1 ) by pea crop 4.27 Effect of integrated application of VAM, phosphorus and irrigation on total Fe, Cu, Zn and Mn uptake (mg kg -1 ) by pea crop 4.28 Effect of integrated application of VAM, phosphorus and irrigation on total B and Mo uptake (mg kg -1 ) by pea crop 4.29 Effect of integrated application of VAM, phosphorus and irrigation on soil ph and organic carbon status (g kg -1 ) after pea harvest 4.30 Effect of integrated application of VAM, phosphorus and irrigation on available N, P and K status (kg ha -1 ) of soil after pea harvest 4.31 Effect of integrated application of VAM, phosphorus and irrigation on exchangeable Ca and Mg status (c mol (p+) kg -1 ) of soil after pea harvest 4.32 Effect of integrated application of VAM, phosphorus and irrigation on available Fe, Zn, Cu and Mn status (mg kg -1 ) of soil after pea harvest 4.33 Effect of integrated application of VAM, phosphorus and irrigation on available B and Mo status (mg kg -1 ) of soil after pea harvest Page No Economic analysis of experiment under pea Phosphorus transformation (mg kg -1 ) in soil as affected by various treatments after completion of two cropping cycles of okra-pea sequence ( ) 197 vii

12 S. No. Title 4.36 Soil physical properties as influenced by various treatments after completion of two cropping cycles in okra-pea sequence ( ) 4.37 Relationship between different P fractions with available P, yield and P uptake by okra and pea Page No Economic analysis of experiment under okra-pea sequence ( ) Economic analysis of experiment under okra-pea sequence ( ) 212 viii

13 LIST OF FIGURES S. No. Title Page No. 3.1 Agroclimatic zone map of H.P. (India), showing the zone of study (wet temperate zone) Mean weekly weather data for the year Mean weekly weather data for the year Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 90 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 90 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) in okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on 57 ix

14 S. No. Title Page No. dry matter accumulation (g plant -1 ) in okra at 90 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) in okra at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) in okra at 90 DAS during Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting depth (cm) of okra during Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting depth (cm) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root weight density (gm -3 ) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root weight density (gm -3 ) of okra during Effect of integrated application of VAM, phosphorus and irrigation on root colonization with VAM (% ) of okra during Effect of integrated application of VAM, phosphorus and irrigation on on root colonization with VAM (% ) in okra during Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 50 DAS during x

15 S. No. Title 4.24 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on plant height of pea (cm) at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry weight accumulation (g plant -1 ) of pea at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry weight accumulation (g plant -1 ) of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry weight accumulation (g plant -1 ) of pea at 50 DAS during Effect of integrated application of VAM, phosphorus and irrigation on dry weight accumulation (g plant -1 ) of pea at 100 DAS during Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting depth (c m) of pea during Page No Effect of integrated application of VAM, phosphorus and irrigation on 151 xi

16 S. No. Title Page No. maximum rooting depth (cm) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of pea during Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of pea during Effect of integrated application of VAM, phosphorus and irrigation on VAM root colonization (%) of pea during Effect of integrated application of VAM, phosphorus and irrigation on VAM root colonization (%) of pea during xii

17 LIST OF PLATES S. No. Title Page No. 3.1 A view of experimental okra crop during A view of experimental pea crop during Response of okra roots to integrated application of VAM, P and irrigation during Root colonization with VAM (%) in okra under integrated application of VAM, P and irrigation during Response of pea roots to integrated application of VAM, P and irrigation during Root colonization with VAM (%) in pea under integrated application of VAM, P and irrigation during xiii

18 LIST OF APPENDICES S. No. Title Page No. 1 Mean weekly weather data at Palampur during (June 2009 to May 2010) Mean weekly weather data at Palampur during (June 2010 to May 2011) Effect of integrated application of VAM, phosphorus and irrigation on N, P and K concentration (%) in okra fruit and stover Effect of integrated application of VAM, phosphorus and irrigation on B and Mo concentration (mg kg -1 ) in okra fruit and stover Effect of integrated application of VAM, phosphorus and irrigation on N, P and K contents (%) in pea pod and stover Effect of integrated application of VAM, phosphorus and irrigation on Zn, Cu and Mn concentration (mg kg -1 ) in pea pod and stover Effect of integrated application of VAM, phosphorus and irrigation on B and Zn concentration (mg kg -1 ) in pea pod and stover Moisture content (%) in okra fruits/ pea pods and stover 254 xiv

19 Department of Soil Science CSK Himachal Pradesh Krishi Vishvavidyalaya Palampur Title of thesis : Phosphorus and rain-harvested water economy through Vesicular Arbuscular Mycorrhizae (VAM) in okra-pea sequence Name of student : Anil Kumar Admission number : A Major discipline : Soil Science Minor discipline(s) : (i) Agronomy (ii) Vegetable Science Date of thesis : July 18, 2012 submission Total pages of thesis : 254 Major Advisor : Dr. V.K. Suri ABSTRACT The present study was carried out during with the aim of economizing phosphorus and rainharvested water through vesicular arbuscular mycorrhizal (VAM) fungi in okra-pea sequence. Use of VAM is highly desirable today from the perspective of meeting nutrient needs of crops efficiently and economically, rationalizing water use and maintaining soil health. Above work consisted of 14 treatments viz. 2 VAM levels (0 & 12 kg ha -1 ), 3 phosphorus levels (50, 75 & 100% of soil test based recommended dose) and 2 irrigation regimes (40 & 80% of available soil water holding capacity) and 2 controls (farmers nutrient practice and generalized recommended dose (NPK). Above treatments were laid out in a completely randomized block design (RBD) with 3 replications. The data on yield attributes, yields, nutrient uptake, net returns and B:C ratios in okra-pea sequence indicated that treatment VAM + 75 per cent soil test based recommended P dose at either of 2 irrigation regimes did not differ significantly than generalized recommended dose and VAM per cent soil test based recommended P dose. It suggests an economy of about 25 per cent in soil test based P dose through seed inoculation with mycorrhizal culture (VAM). The use of mycorrhizal biofertilizer (VAM) enhanced water use efficiency of okra and pea crop by about 5-17 and per cent, respectively. Integrated application of VAM, P and irrigation did not alter available soil nutrient status significantly, however, available P status was enhanced by per cent after harvest of each of the two crops i.e. okra and pea. Further, after completion of two years of okra-pea sequential cropping, integrated application of VAM, P and irrigation enhanced water holding capacity and mean weight diameter of soil particles by 5-6 and 4-9 per cent, respectively. Above practice evaluated in okra-pea sequence for two years, led to higher status of water soluble-p (10-32%), NaHCO 3 -Pi (8-13%), NaOH-Pi (5-13%) and low status of organic-p (NaHCO 3 -P o & NaOH-P o ), each one of which contributed appreciably to available P supply to plants. Results of the current study suggest that the practice of VAM inoculation can go a long way in reducing the cost of production directly as well as otherwise. Moreover, its continuous use is going to enhance crop quality and overall soil fertility, which is the need of the hour. (Anil Kumar) Student Date (Dr. V.K. Suri) Major Advisor Date: Head of Department xv

20 Department of Soil Science CSK Himachal Pradesh Krishi Vishvavidyalaya Palampur Title of thesis : Phosphorus and rain-harvested water economy through Vesicular Arbuscular Mycorrhizae (VAM) in okra-pea sequence Name of student : Anil Kumar Admission number : A Major discipline : Soil Science Minor discipline(s) : (i) Agronomy (ii) Vegetable Science Date of thesis : July 18, 2012 submission Total pages of thesis : 254 Major Advisor : Dr. V.K. Suri ABSTRACT The present study was carried out during with the aim of economizing phosphorus and rainharvested water through vesicular arbuscular mycorrhizal (VAM) fungi in okra-pea sequence. Use of VAM is highly desirable today from the perspective of meeting nutrient needs of crops efficiently and economically, rationalizing water use and maintaining soil health. Above work consisted of 14 treatments viz. 2 VAM levels (0 & 12 kg ha -1 ), 3 phosphorus levels (50, 75 & 100% of soil test based recommended dose) and 2 irrigation regimes (40 & 80% of available soil water holding capacity) and 2 controls (farmers nutrient practice and generalized recommended dose (NPK). Above treatments were laid out in a completely randomized block design (RBD) with 3 replications. The data on yield attributes, yields, nutrient uptake, net returns and B:C ratios in okra-pea sequence indicated that treatment VAM + 75 per cent soil test based recommended P dose at either of 2 irrigation regimes did not differ significantly than generalized recommended dose and VAM per cent soil test based recommended P dose. It suggests an economy of about 25 per cent in soil test based P dose through seed inoculation with mycorrhizal culture (VAM). The use of mycorrhizal biofertilizer (VAM) enhanced water use efficiency of okra and pea crop by about 5-17 and per cent, respectively. Integrated application of VAM, P and irrigation did not alter available soil nutrient status significantly, however, available P status was enhanced by per cent after harvest of each of the two crops i.e. okra and pea. Further, after completion of two years of okra-pea sequential cropping, integrated application of VAM, P and irrigation enhanced water holding capacity and mean weight diameter of soil particles by 5-6 and 4-9 per cent, respectively. Above practice evaluated in okra-pea sequence for two years, led to higher status of water soluble-p (10-32%), NaHCO 3 -Pi (8-13%), NaOH-Pi (5-13%) and low status of organic-p (NaHCO 3 -P o & NaOH-P o ), each one of which contributed appreciably to available P supply to plants. Results of the current study suggest that the practice of VAM inoculation can go a long way in reducing the cost of production directly as well as otherwise. Moreover, its continuous use is going to enhance crop quality and overall soil fertility, which is the need of the hour. (Anil Kumar) Student Date Head of Department (Dr. V.K. Suri) Major Advisor Date: Dean, Postgraduate Studies xvi

21 1 1. INTRODUCTION The facts reveal that on one hand, the world population is increasing continuously whereas, on the other hand, food grain production is not increasing proportionately due to various factors such as decline in soil fertility and repercussions arising from climate change phenomenon as manifested by unpredictable patterns of rainfall and temperature. The major reason for poor soil health in India seems to be the unbalanced nutrient application. Amongst, various strategies to cope with above situation, soil test based integrated nutrient management holds the key to reverse above trend leading to restoration of soil fertility and in turn, boosting crop production and productivity. Next to nitrogen, phosphorus is the most important nutrient element globally. It acts as an important structural component of cell constituents (cell membrane, chloroplasts & mitochondria) and metabolically active compounds. Phosphorus is a component of some important compounds viz. sugar phosphates (ADP & ATP), nucleic acids, nucleoproteins, nucleotides, NADP, pyridoxyl phosphate and thiamine pyrophosphate. Above compounds actually play an important role in growth (cell division and elongation), photosynthesis, respiration, energy storage/ transfer and several other processes in plants. As such, phosphorus promotes early root formation and overall growth, thereby, hastening maturity. Being a component of RNA and nucleoproteins, P improves the quality of fruits, vegetables and that of food grain crops (Singh 1996). Barring the situation around neutral ph, phosphorus availability to plants is a major constraint in both acid and alkaline soils, its average efficiency being per cent. In case of acid soils, much of the applied phosphorus may react with Fe and Al ions (existing in insoluble and exchangeable forms) thereby, getting precipitated/ fixed as Fe and Al hydroxyl phosphates and thus, becoming unavailable for plant use (Sharma et al. 1980). In alkaline soils, much of it may react with Ca 2+ ion (existing in above forms) thereby, getting precipitated as Ca hydroxyl phosphate, thereby becoming out of bounds for plant use (Brady 2002). In both the above situations, the concentration of P in the soil solution is in micromolar range, besides a slow rate of P diffusion in the soil. Hence, depletion of P in the root zone commonly limits further uptake of P by existing roots and potentially by the plants as a whole.

22 2 In Himachal Pradesh, majority of farmers are small and marginal. They are unable to apply chemical fertilizers in recommended amounts because of their low purchasing power, small and scattered land holdings, remoteness, rainfed/ subsistence nature of farming and lack of awareness about new technologies, etc. Phosphorus is the costliest fertilizer and farmers apply a nominal amount of it to their crops due to obvious reasons. The area to which present work is targeted covers acid soils which represent about 33 per cent of cultivable land in Himachal Pradesh (Anonymous 2004). About 80 per cent of arable area in Himachal Pradesh is rain fed. About 4/5ths (>80%) of total rainfall occurs during just four months of the year (June to September). Unfortunately, most of the rain water get wasted by way of excess run-off in streams, rivers, etc. carrying along with it fertile soil and nutrients. Run-off water could be harvested and stored in the farm ponds followed by its judicious utilization particularly in vegetable crops, which are more remunerative. However, in acid soil, especially of high rainfall regions such as Palam Valley, phosphorus availability is much limited because of quick fixation of most of the applied P as insoluble phosphate complexes by way of reaction with soil Al and Fe ions (Sharma et al. 1980). Phosphorus and harvested rain water are costly commodities and therefore, must be used efficiently with the aim of getting the maximum economic returns to the farmers. Incidentally, mycorrhizal biofertlizer (VAM), which is an inexpensive and ecofriendly input, is capable of enhancing both P availability and water-use efficiency of crops. The VAM symbiosis refers to a mutualistic, symbiotic relationship formed between fungi and living roots of higher plants (Harley and Smith 1983; Sieverding 1991). Mycorrhizae are associated with plants either upon root surfaces (ectomycorrhizae) or inside root tissues (endomycorrhizae). The VAM fungi are a common member of endomycorrhizae. The VAM symbiosis is characterized by fungal structures inside roots, namely hyphae, arbuscules (highly branched structures) and vesicles (drop-shaped storage organs, not always present). The VAM fungi receive carbon compounds/ nutritional requirements from host plant roots. In turn, they supply to the plants nutrients such as nitrogen, phosphorus, potassium, calcium, copper, zinc and other trace elements, etc, absorbed by them from the soil (Barea and Jeffries 1995).

23 3 Over 95 per cent of plants form mycorrhizae. However, members of Brassicaceae and Chenopodiaceae families do not form above association. The VAM fungi do so by expanding the surface area of plant root system by 10 to 1000 fold into the soil through their ramifying hyphae, thereby increasing their exploratory area for harnessing both phosphorus and water (Marshner and Dell 1994). Above fungi solubilise inorganic forms of P through release of low molecular weight organic acids (oxalic, malic acids, etc.). Above compounds solubilise insoluble phosphates by lowering soil ph, causing chelation of Fe and Al cations and competing with phosphate ions for adsorption sites on soil exchange complex, thereby releasing P into soil solution for plant use (Zou et al. 1995; Nahas 1996). Further, through secretion of a number of enzymes (chitinase, peroxidase, cellulase, protease, phosphatase, etc.), VAM fungi attack complex organic compounds converting them into simple ones, that can be absorbed and used by fungi/ host plants to meet their energy needs for growth and reproduction (Chen et al. 2007). Combined use of mycorrhizal biofertilizer (VAM) with 75 per cent soil test based recommended P dose improved yield and quality of wheat, soybean, maize and okra to the same extent as 100 per cent P application, indicating thereby a saving of 25 per cent fertilizer phosphorus (Suri et al. 2010; Kumar 2010). Himachal Pradesh has favourable soil and climatic conditions for cultivation of various vegetable crops, which are far more profitable than the traditional cereal based cropping systems. As such, it is worthwhile that the farmers should divert a portion of their land from conventional rice (or maize)-wheat sequence to a profitable and sustainable vegetable based cropping sequences. One of the crops in such a sequence should preferably be a legume crop. Legume crops enhance soil fertility and being rich in protein, help provide nutritional security to the farmers. Okra (Abelmoschus esculentus L.) is an important vegetable crop. Being a rich source of P, Fe and Ca, it occupies an important place in human diet. Likewise, garden pea (Pisum sativum L.) being very palatable, nutritious and is amenable to preservation. Presently, it is fetching a high premium in the local and super vegetable markets. The area under pea is increasing rapidly in the state especially under high and mid-hill zones, leaving behind the most important and major vegetable crop i.e. potato. Actually, okra and pea are somewhat moderate in their water and nutrient requirements, apart from being well suited for cultivation under mid-hills wet temperate zone of Himachal Pradesh.

24 4 Based on above facts, planned study appears to be quite pertinent to Palam Valley due to acidic nature of soils (ph 5.2) and wet temperate climate. Currently, information on the role of VAM fungi vis-à-vis P and irrigation water economy in vegetables is lacking and needs to be generated urgently so that necessary recommendations can be made to farmers of the area. As such, the present investigation entitled Phosphorus and rain-harvested water economy through vesicular arbuscular mycorrhizae (VAM) in okrapea sequence has been carried out at Research Farm, CSK HPKV, Palampur with the broad aim of assessing P and rain-harvested water economy through VAM inoculation with following specific objectives: i. The impact of VAM on phosphorus and water-use-efficiency in okra-pea sequence ii. iii. iv. To study changes in some important soil physico-chemical properties Impact of different treatments on soil P fractions To work out economics of different treatments

25 5 2. REVIEW OF LITERATURE The food needs of burgeoning world population have to be met largely through sharp increases in crop production from the existing land by all possible methods. One of the most important strategies particularly in the wake of intense energy crisis, is the improvement in fertilizer phosphorus use efficiency, which is the lowest amongst plant nutrients. Fertilizer phosphorus has contributed tremendously towards increasing food production, yet even with best agronomic practices, the recovery of fertilizer phosphorus hardly exceeds per cent, because most of the applied phosphorus gets precipitated/ fixed and becomes unavailable for plant use. A number of approaches such as liming, sub-soil placement, application of P in splits and dipping of seedlings into soluble P slurry, etc. aimed at increasing phosphorus use efficiency have been developed in India and abroad, but none of the strategies is equally effective under different situations. Therefore, there is an urgent need to attempt some alternative approach to tackle the problem of low phosphorus use efficiency. Secondly, about 80 per cent of arable area in Himachal Pradesh is rain fed. About 4/5ths of total rainfall occurs during just one quarter of the year i.e. June to September. Unfortunately, most of rain water received gets wasted by way of excess run off in streams, rivers, etc. carrying along with it fertile soil and nutrients, besides causing several environmental repercussions. Run off water could be harvested and stored in the farm ponds followed by its judicious utilization in vegetable crops, which are more remunerative. In the light of above scenario, exploitation of mycorrhizal (VAM) biofertilzer may be a good proposition, as it has the ability to solubilise and mobilise phosphorus from soil and applied fertilizers and use water efficiently. The information available on various aspects of the subject is discussed in the following paragraphs under various heads viz.: 2.1 Fate of applied phosphorus in acid soils 2.2 Response of crops to phosphorus application 2.3 Practical significance of vesicular arbuscular mycorrhizal (VAM) fungi

26 6 2.4 Effect of integrated application of VAM, P and irrigation on various plant characters and soil properties 2.5 Influence of VAM and P application on the status of different forms of P in soils 2.1 Fate of applied phosphorus in acid soils Acid soils occupy 39.5 million square kilometres area globally, which is about 25.9 per cent of total geographical area. Out of the total cultivatable area (141 m ha) in India, approximately 49 m ha of land suffers from soil acidity. Out of 49 m ha area, 25.9 m ha have ph<5.6 and 23.1 m ha has ph ranging between 5.6 to 6.5 (Sharma and Sarkar 2005). In Himachal Pradesh, acid soils occupy about 33 per cent of the total cultivated area. Humid regions, where rainfall exceeds evapotranspiration are more prone to acid soil formation. In such regions, high rainfall causes excessive leaching of bases from soil surface and results in the formation of acid soils. The partly decomposed organic matter is also responsible for the formation of above soils. There is an acute deficiency of phosphorus in acid soils which, makes it the most limiting nutrient for crop production in above soils. Under normal conditions, most of the phosphorus added through chemical fertilizers is water soluble and therefore, readily available to plants. But, in case of acid soils, applied phosphorus gradually reacts with Fe and Al compounds present in the soil and consequently, gets transformed into relatively insoluble compounds (variscite and strengite), which are hardly available to plants (Brady 2002). The soils of hilly and mountainous areas of Himachal Pradesh are generally found to be P deficient due to their acidic nature (Sharma et al. 1980). The concerned workers have attributed this fact to high P-fixing capacity of above soils due to high concentration of Fe and Al ions. Sattell and Morris (1992) reported that moderately labile organic P fraction as well as labile inorganic P fraction contributed significantly to P uptake under acid soil condition. Parfitt (1999) found that in acid soils, P gets pre-dominantly adsorbed by Al/ Fe oxides and hydroxides present in soil. Actually, Fe/Al oxides in soils have a large specific surface area, which results into a great number of adsorption sites for P fixation (Hinsinger 2001).

27 7 Swarup et al. (2001) observed a steady decline in available P status with continuous cropping without P application (100 % N alone). In acid soils, Al-P is more easily available to upland crops than Fe-P. Further, it is observed that amorphous sesquioxides (Fe and Al oxides) release P much more easily than their crystalline forms due to obvious reasons. Pattanayak et al. (2001) reported that combined application of lime and P had synergetic effect on improving available P status in acid soils. Waigwa et al. (2003) reported that rock phosphate coupled with FYM or maize stover generally, increased P availability in acid soils of Kenya. Results of a long term fertilizer experiment carried out on an acid soil (Sharma et al. 2003) revealed that out of total amount of P (100% of GRD) applied to crops, only 9-19 per cent was removed by crops under different treatments. The remaining amount was retained by the soil. Sharma and Sarkar (2005) found a low (15-20%) apparent recovery of applied P in an acid soil, indicating conversion of applied P into insoluble forms. Luengo et al. (2006) reported that in an acid soil, P can be adsorbed on surface of clay minerals and Fe/Al oxides by forming various complexes. Uptake of P by plants from colloidal Al-P is considerably higher than that from colloidal Fe- P in acid soils (ph 4.8). The reason for this is a faster rate of crystallization of Fe-P than Al-P and a greater reduction in surface area. In general, P fixation decreases with increase in ph and degree of base saturation in acid soils (Pattnayak et al. 2009). It is summarized from above reports that phosphorus availability is a major constraint in acid soils, because of quick reactions of applied P with Fe and Al compounds present in above soils. 2.2 Response of crops to phosphorus application Second only to nitrogen, phosphorus is the most important nutrient element globally. It acts as an important structural component of cell constituents (cell membranes, chloroplasts & mitochondria) and metabolically active compounds. Some important compounds of which P is a component are viz. sugar phosphates (ADP & ATP), nucleic acids, nucleoproteins, nucleotides, NADP, pyridoxyl phosphate and thiamine pyrophosphate. Above compounds actually play an important role in growth

28 8 (cell division and elongation), photosynthesis, respiration, energy storage/ transfer and several other processes in plants. As such, phosphorus promotes early root formation, overall growth thereby, hastening maturity. Phosphorus application improves the quality of fruits, vegetables and that of food grain crops, it being a component of RNA and nucleoproteins (Pattanayak et al. 2009). Singh and Singh (1990) studied the response of French bean to P application in an acid Alfisol, deficient in available P. Application of 100 per cent P dose (soil test based), influenced green pod yield significantly. Response of above crop in terms of productivity varied in the range of 15 to 25 per cent as P levels increased from 28 to 42 kg P 2 O 5 ha -1. In a field study conducted with okra involving temperate situation and neutral ph soil, Bahadur and Singh (1990) found that application of 80 kg P 2 O 5 ha -1 gave 79.5, 41.0 and 53.0 per cent higher plant height, pod length and green pod yield, respectively over treatment involving no P input. It is attributable to the reason that phosphate being one of the components of RNA and DNA molecules, played a vital role in energy transfer for various metabolic processes. In a field study conducted under the dry temperate condition, Shekhar and Sharma (1991) reported a higher (20%) productivity of garden pea under 70 kg P 2 O 5 ha -1 than control (N o P o K o ). Further, above treatment increased pod length and pod weight by 9.0 and 7.4 per cent, respectively over control. Arora et al. (1991) reported 18 per cent higher okra fruit yield under 60 kg P 2 O 5 ha -1 than the treatment involving no P application. Further, application of 60 kg P 2 O 5 ha -1 coupled with 90 kg N ha -1 gave 41 per cent higher yield as compared to application of 60 kg P 2 O 5 ha -1 alone. In a field experiment, conducted under temperate condition involving an acid Alfisol, Sharma and Singh (1991) reported that application of 66 kg P 2 O 5 ha -1 gave 85.3 per cent higher P uptake by potato tubers than absolute control. In case of radish, uptake was 46.3 per cent higher than control. Findings of a field experiment carried out on an acid soil involving 3 phosphorus sources revealed that application of P as SSP was more beneficial to pea crop than application of P as Mussoorie rock phosphate (MRP) and Purulia rock phosphate (PRP). Further, aplication of P as SSP enhanced available P status of soil as well as P concentration in pea plants (Datta et al. 1993).

29 9 Application of 75 kg P 2 O 5 ha -1 improved onion yield by 14.5, P uptake by 24.3 and P use efficiency by 26.0 per cent, respectively over absolute control under wet temperate condition involving an acid soil (Sharma and Raina 1994). In another experiment, Chaudhary et al. (1995) found highest okra fruit yield (88.5q ha -1 ) with application of 50 kg P 2 O 5 ha -1, which was almost 1.5 times higher than control. Jaggi et al. (1995) reported that application of phosphorus upto 60 kg P 2 O 5 ha -1 increased potato tuber yield and P uptake significantly in an acid soil (ph 5.6) of temperate region. The combined application of 60 kg P 2 O 5 ha -1 and FYM 3.2 t ha -1 revealed a synergistic interaction effect on uptake of N, P and K thereby, increasing potato tuber yield accordingly. The pooling of data belonging to a 2 year experiment resulted into 19.3 t ha -1 potato tuber yield in above treatment. In a field experiment conducted at Kanpur (warm and humid climate), Prasad and Prasad (1998) reported that application of 90 kg P 2 O 5 ha -1 gave respective increases of 11.3 and 11.2 per cent in protein content (pea seeds) over control, during first and second years of experimentation. Bhat and Dhar (1999) found that application of 70 kg P 2 O 5 ha -1 gave respective significant increases of 32.2 and 16.5 per cent in okra seed yield over application of 50 and 60 kg P 2 O 5 ha -1 under wet temperate climatic condition. In an experiment with garden pea involving a loamy soil, Singh et al. (2004) reported that application of 69 kg P 2 O 5 ha -1 increased pod length, number of pods per plant, seed yield and stover yield by 9.2, 17.0, 9.3 and 9.3 per cent, respectively over application of 45 kg P 2 O 5 ha -1. Above results are attributable to the role of phosphorus in stimulating plant growth in respect of above parameters due to rapid cell division and elongation. In a field study with potato conducted in temperate region covering acid soils, Sud (2005) reported that application of 100 per cent generalized recommended P dose as SSP increased dry matter yield, P concentration in shoot and its uptake significantly by 10.9, 10.2 and 22.8 per cent, respectively over control (no P application). Further, FYM incorporation in soil gave respective increases of 18.8 and 32.3 per cent in dry matter yield and P uptake, respectively over control.

30 10 In another experiment with okra involving above soil and climatic condition, Oluwatoyinbo et al. (2005) observed that plant height, dry matter and fruit yield of okra increased significantly by 20, 23 and 19 per cent following 100 per cent (50 kg ha -1 ) soil test based recommended P application, respectively over control (P 0 ). Okon et al. (2005) carried out an experiment with onion in an acid soil (ph 4.9). Results revealed that application of 40 kg P 2 O 5 ha -1 gave 78 per cent higher okra fruit yield over absolute control. Akineinde and Adigun (2005) found that application of 50 kg P 2 O 5 ha -1 produced tallest okra plants, which were grown under temperate climatic condition involving an acid soil. Results of a field experiment conducted during rainy season in an acid laterite soil of West Bengal revealed that application of P (50% RP + 50% SSP) + phosphate solublising bacteria (PSB) gave significantly higher (28.2 & 8.9%) yield of pigeon pea, respectively over control (no phosphorus) and application of 100 per cent of recommended P dose as SSP alone. Above treatment also gave highest (18.3%), P uptake than application of 100 per cent of recommended P dose as SSP alone (Dutta 2007). Saha et al. (2007) reported that application of 60 kg P 2 O 5 ha -1 gave 13.7 per cent higher pea green pod yield than control (P 0 ) in an acid soil. In a field experiment conducted on a medium P rating soil, Tripathi and Maity (2009) reported highest values of ascorbic acid (18.23 mg 100 g -1 ) and crude protein (19.9%) under 50 kg P 2 O 5 ha -1 treatment. In another study, application of 40 kg P 2 O 5 ha -1 gave 62 per cent higher okra fruit yield over absolute control (Oluwatoyinbo et al. 2009). The findings of a field experiment conducted by Bairwa et al. (2009) under warm and humid climate involving a P deficient soil, revealed that application of 45 kg P 2 O 5 ha - 1 increased okra fruit yield significantly by 29.3 per cent over absolute control. Above treatment also gave the highest benefit cost ratio (3.19) and P content (1.06%) in stover. It can be inferred from the above survey of literature that phosphorus plays an important role in improving growth, productivity and quality of various crops.

31 Practical significance of vesicular arbuscular mycorrhizal (VAM) fungi The soil is a good habitat for many agriculturally beneficial microbes including mycorrhizal fungi. Mycorrhizae belong to kingdom fungi, division Glomeromycota, class Glomeromycetes, order Glomerales and family Glomeraceae (Mehrotra and Aneja 2003). Above fungi are associated with plants either upon root surfaces (ectomycorrhizae) or inside root tissues (endomycorrhizae). The VAM fungi are a common member of endomycorrhizae. While fungi obtain carbon compounds/ nutritional requirements from host plant roots, in turn, they supply plant nutrients such as N, P, K, Ca, Cu, Zn, etc, which are absorbed by them from the soil (Barea and Jeffries 1995). Many workers have reported an increase in plant growth resulting from above VAM association and the same has been attributed by them to increased mineral element uptake mediated by VAM hyphae in the soil, improved soil-plant-water relations and plant tolerance to a variety of abiotic stresses, etc. (Harrier and Watson 2003; Smith and Read 2008) VAM fungi mediated nutrient absorption and utilization It is widely observed that total P levels in most soils are increasing, despite its decreasing availability, globally for crop production. It is less available for plant growth, especially in plants lacking specific adaptation mechanisms to P deficiency (Jones 1998). The various agronomic approaches aimed at enhancing P use efficiency are: liming, subsoil placement, application of P in splits and dipping of seedlings into soluble P slurry, etc (Singh 1996). Several workers have tried above approaches under various soils and climatic situations. Each strategy involves its merits and demerits. Further, it seems that in high rainfall regions, most of the nutrients leach away (NO 3 -N, S, Ca, K, B, Mo, etc.) from the normal root zone, thus becoming unavailable to plants. As such, there is a dire need to explore different natural microbial associations in different cropping systems, which may efficiently access P and make it available to plants for utilization. In above scenario, mycorrhizal biofertilizer (VAM) may be a good proposition to enhance P use efficiencies of crops. The VAM fungi do so by extending root system into the soil through ramifying hyphae thereby increasing its exploratory area for harnessing both phosphorus and water. Above fungi not only meet out nutrient requirements of crops

32 12 but, also confer other associated benefits on plants such as increased resistance to diseases, drought, soil salinity and also enhance N 2 fixation in legumes. Many workers have reported increased uptake of nutrients such as N, P, K, Ca, Mg, Fe, Zn, Cu and Mn in plants, inoculated with VAM culture in a variety of soil and climatic conditions (Azaizeh et al. 1995; Degens et al.1996; Smith and Read 1998; Hodge et al. 2001; Kumar 2010). Lambert and Weidensaul (1991) worked with an acid soil and reported significantly higher (12 & 15%) concentration of Cu and Zn, respectively in VAM inoculated soybean plants than non inoculated ones. In another experiment carried out on above soil, George et al. (1994) reported significantly higher concentration of nutrients (Fe, Zn and Cu) in mycorrhizal plants as compared to non-mycorrhizal ones. Further, the concentration of Mn in stover of VAM inoculated plants was lower than that in nonmycorrhizal ones. In an experiment covering P deficient soils, Li et al. (1991) concluded that VAM hyphae absorbed P from deeper soil layers, where host roots failed to reach. In addition, VAM root colonization changed root architecture, which in turn, increased root-soil interaction vis-à-vis nutrient exploration (Atkinson 1994). In a field study conducted with a clay-loam soil under temperate condition, Goicoechea et al. (1997) reported that combined use of VAM and Rhizobium enhanced nutrient (N, K, Ca, Mg, Zn, Mn, Cu, Na, Fe and B) contents in alfalfa plants significantly than control (no biofertilizer application). In another field experiment conducted on a P deficient soil, Bryla and Duniway (1997) reported an increase of 39 per cent in P uptake by VAM inoculated plants than non-inoculated ones. Further, mycorrhizal plants gave 28 per cent higher shoot dry weight as compared to non-mycorrhizal ones. Clark and Zeto (2000) reported significant enhancement in N, K, Ca, Mg, Zn, and Fe and Cu uptake under VAM inoculation involving treatments in field experiments conducted by them on both acid and alkaline soils. Sorial (2001) studied the effect of VAM on P uptake by wheat covering P deficient soils. Results revealed that VAM inoculation enhanced P uptake by 26 per cent under moisture stress situation as compared to non-inoculated ones.

33 13 Kalipada and Singh (2003) in an experiment on a sandy loam soil (ph 7.0), reported that inoculation of chickpea with VAM culture enhanced P uptake and yield by 14 and 12 per cent, respectively over PSB applications alone. Further, yield and nutrient uptake increased with increasing levels of P. In an experiment with cowpea involving a sandy clay loam soil, Rabie and Humiany (2004) found that combined application of VAM, PSB and 25 per cent of generalized recommended N dose increased N, P and K uptake by 39, 14 and 13 per cent, respectively than sole application of 100 per cent generalized recommended dose of N. In a field study conducted at Pantanagar, Singh et al. (2004) observed that application of VAM + 50 per cent P 2 O 5 (generalized recommended dose/ GRD) gave 16, 70 and 41 per cent higher N, P and K uptake by pea, respectively, than application of 100 per cent P dose (GRD) only. Further, uptake of N, P and K by okra increased by 62, 43 and 28 per cent in above treatment over sole application of 100 per cent P dose (GRD) VAM fungi mediated water absorption and utilization The VAM symbiosis often results in altered rates of water movement into, through and out of host plants, with consequent effects on tissue hydration and leaf physiology. Mycorrhizal fungi (VAM), which is an inexpensive and eco-friendly input, is capable of enhancing water-use efficiency of crops. The VAM fungi do so by extending root system into the soil through ramifying hyphae thereby increasing its exploratory area for harnessing both phosphorus and water. Mycorrhizal hyphae penetrate soil pores inaccessible to root hairs thereby absorbing water which is not available to nonmycorrhizal plants (Koide 1993; Farahani et al. 2008). According to Hardie and Leyton (1981), higher water use efficiency in mycorrhizal plants might be due to higher ability of roots to absorb soil moisture, thereby maintaining stomata in open condition. Enhanced water conductivity is attributable to increased surface area for water uptake provided by fungal hyphae in the soil. The high dry matter production, following VAM inoculation might partially explain why mycorrhizal plants gave higher water use efficiency (WUE) than non-mycorrhizal ones (Duan et al. 1996; Al-Karaki and Al-Radded 1997).

34 14 Another reason for higher WUE in case of mycorrhizal plants is the development of more roots as well as requirement of more water to sustain high growth rate, which might have resulted into a greater water use by mycorrhizal plants (Nagarathna et al. 2007). Farahani et al. (2008) further attributed higher WUE to a greater absorption of water and P by plants thereby, boosting biological yield. Actually, each factor which promotes biological yield would naturally enhance WUE also. In a green house experiment, Yusnaini et al. (1999) found that seed inoculation of corn with VAM culture improved plant water status and enhanced yield significantly. In an experiment conducted in Iran involving a sandy-loam soil, Farahani et al. (2008) reported that application of VAM along with 100 per cent generalized recommended dose of P in coriander, enhanced WUE (32%) significantly than non-inoculated ones at same level of applied P. Porcel and Juan (2004) conducted a field experiment with soybean and reported similar leaf water potential in mycorrhizal and non-mycorrhizal plants grown under wellwatered condition. However, under drought stress condition, water potential was 32 per cent less in mycorrhizal plants as compared to non-mycorrhizal ones. In another study, conducted with mung bean involving a low P sandy loam soil, Singh and Idani (2007) found that VAM inoculation + furrow planting improved WUE by 1.7 per cent over control i.e. VAM inoculation + flat bed planting. Based on above information, it is concluded that VAM inoculation improved nutrient and water absorption from soil significantly especially under phosphorus and water stressed situations. 2.4 Effect of integrated application of VAM, P and irrigation on various plant characters and soil properties The use of biofertilizers along with chemical fertilizers plays an important role in boosting agricultural production. Above practice enhances seed germination, crop growth, crop quality, nutrient availability in soils (especially N, P, K and micronutrients) as well as overall soil fertility. Biofertilizers, which are actually applied as microbial inoculants are aimed at enhancing the number/ activity of beneficial micro-organisms in the rhizosphere recommended for the given situation. Apart from meeting out nutrient requirements of crops partially, biofertilizers also confer many other benefits on plants

35 15 such as increased resistance to diseases, drought, soil salinity and also enhance N 2 fixation in legumes. i. Plant characters In an experiment, involving a neutral ph soil having medium available P status, Kothari et al. (1990) reported that inoculation of maize with VAM culture, increased root length and root weight density by 17 and 35 per cent, respectively than non-inoculated ones. Li et al. (1994) conducted a pot experiment and reported that soil inoculation with VAM increased relative leaf water content, plant height, leaf area, stem thickness and plant fresh weight than non-inoculated ones. While working with maize in an Alfisol categorized low in organic matter with ph 6.8, Osonubi (1994) reported significantly higher leaf area (18.4 & 13.9 m 2 plant -1 ) in VAM inoculated plants, under both well watered and water stressed conditions, respectively than non-mycorrhizal ones. Xylem water potential was significantly lower (16%) in VAM inoculated plants as compared to non-mycorrhizal ones under drought stressed condition. In a field study with tomato, involving low available P soil, Edathil et al. (1996) found respective increases of 61, 24 and 53 per cent in leaf area, shoot and root length of tomato with application of VAM (Glomus aggregatum) over control (no VAM). Further, N, P and Zn concentrations increased by 37, 26 and 17 per cent, respectively over control with application of VAM culture. However, K and Cu contents in plants were found to be statistically similar under inoculated and uninoculated situations. In another experiment, involving a clay loam soil rating low in available P, Solaiman and Hirata (1997) reported that combined application of VAM culture and 100 per cent generalized recommended dose (GRD) of P gave significantly higher (68%) pea green pod yield as compared to absolute control. Dhinakaran and Savithri (1997) reported that VAM inoculation in combination with 100 kg P 2 O 5 ha -1 led to an increase of 32 per cent in P use efficiency in potato than sole application of 100 kg P 2 O 5 ha -1. The findings of a field experiment conducted on a sandy loam soil, low in available P status revealed that inoculation of capsicum seedlings with VAM culture at

36 16 lower levels of applied P led to a higher root colonization in comparison with higher levels of applied P (Aguilera et al. 1999). Shirani et al. (2000) reported significantly higher (46%) P use efficiency in wheat involving 5 cm irrigation without VAM inoculation over control. Inoculation of wheat seeds with VAM culture further enhanced above parameter at the same level of irrigation regime as compared to control. In a field study with wheat, conducted in Iran, Shirani and Daneshian (2002) reported 15.3 per cent increase in P use efficiency with application of VAM culture per cent P dose (GRD) treatment than application of 100 per cent P dose only. In a study, involving pot culture with oats (Avena sativa), Khan et al. (2003) found that WUE increased significantly with inoculation of different species of VAM viz, Gigaspora rosea, Glomus intradices+gigaspora and Glomus etunicatum+glomus intradices by 6, 9 and 13 per cent, respectively under 100 per cent field capacity situation and by 8, 12 and 20 per cent under 50 per cent of field capacity situation, respectively than control. In another field experiment with a sandy loam soil in Canada, Xavier and Germida (2003) reported that combined inoculation of VAM and Rhizobium increased shoot growth and yield of pea by 38 and 116 per cent than control (no inoculation). Further, at final harvest, there were respective increases of 24 and 33 per cent in N and P contents in pea plants over control. Root colonization in above treatment was 62 per cent. Under a neutral soil ph condition, combined application of VAM and 75 per cent P 2 O 5 (GRD) gave the same okra fruit yield as given by 100 per cent P 2 O 5 only (Bahadur and Manohar 2001). Both the above treatments gave almost similar values of fruit length, fruit diameter and fruit weight. It can be inferred from above that VAM inoculation economized P dose (GRD) by about 25 per cent. Pandey et al. (2003) studied response of VAM and phosphorus on growth and yield of pea involving an acid soil under cool humid temperate climate. Results revealed that application of 100 per cent generalized recommended P dose coupled with VAM biofertilizer gave significant increases of 8 and 42 per cent in plant height and green pod yield, respectively than sole application of 100 per cent P dose (GRD) as SSP alone. In a field study, conducted on a Mollisol, Singh et al. (2004) found that okra yield obtained under application of VAM + 50 per cent P 2 O 5 was found to be statistically on par with PSB + 75 per cent P 2 O 5 treatment. Above treatments were statistically similar

37 17 with respect to N, P and K uptake in okra fruits and stover. It suggests an economy of about 25 per cent in soil test based P dose in okra. Some workers conducted an experiment with wheat involving an acid Alfisol of wet temperate region. The findings revealed that the combined use of mycorrhizal (VAM) culture, phosphate solubilising bacteria (PSB) and 75 per cent of soil test based P dose as SSP was statistically at par with 100 per cent fertilizer P application in improving yield, suggesting thereby a saving of about 25 per cent fertilizer P (Suri et al. 2006) in wheat. The findings of a field experiment conducted by Kumar and Srivastva (2006) in a P deficient neutral soil revealed that combined application of VAM and 30 kg P 2 O 5 ha -1 resulted in 62 per cent higher tomato fruit yield than application of 100 per cent recommended P through SSP. Further, treatment, VAM + 50 per cent of recommended P dose, gave statistically the same yield as recorded under VAM + 75 per cent of recommended P dose treatment. It can be inferred from above that VAM inoculation economized P dose by about 25 per cent. Auge et al. (2006) reported that while mycorrhizal plants recorded 39 per cent root colonization with VAM application, no colonization was observed under noninoculated ones. Further, VAM inoculation increased root weight density by 16.2 per cent than non-inoculated counterpart. Shoot dry weight increased by 15 per cent in mycorrhizal plants as compared to non mycorrhizal control. In a pot experiment involving alkaline soil categorized as medium in available P, Raiesi and Ghollarata (2006) reported that in case of treatment involving 30 mg kg -1 P application, root colonization with VAM was lower by 44 per cent than treatment involving P application at 10 mg kg -1. A field study was carried out with summer mung bean on a neutral soil rating medium in available P. In above study, VAM inoculation led to higher consumptive use of water (26.1 cm) during crop growth as well as higher water use efficiency (45.7 kg hacm -1 ) than non-inoculated counterpart. Further, yield was 9 per cent higher under VAM inoculated plants than non-inoculated control (Singh and Idani 2007). Amount of shoot biomass produced per unit of water utilized by crop was higher by 20.5 per cent in

38 18 mycorrhizal plants than non-mycorrhizal ones. The WUE increased as P levels increased. However, WUE decreased substantially under moisture stress condition. At moisture levels of 75 and 60 per cent of field capacity (FC), WUE decreased by 3.3 and 12.4 per cent, respectively over moisture level at 100 per cent FC. In general, WUE was higher in mycorrhizal plants at all the levels of applied P as compared to non-mycorrhizal ones. Thenua et al. (2010) reported that two irrigations- first at flowering and second at pod filling, gave higher (1.56 t ha -1 ) yield of chickpea. Further, P in the form of either SSP (1.56 t ha -1 ) or DAP (1.53 t ha -1 ) was better in comparison with rock phosphate (1.40 t ha -1 ). Dual inoculation involving VAM and PSB gave a higher (1.56 t ha -1 ) yield of above crop than absolute control. The findings of a field experiment conducted by Kumar (2010) in a P deficient acid Alfisol of wet temperate region revealed that application of 100 per cent P dose based on soil test, resulted into higher (84 & 96 %) okra fruit yield over control during the first and second years of experimentation. However, above treatment was found to be statistically at par with 75 per cent P 2 O 5 + VAM inoculation treatment. It is obvious from above that use of VAM culture economized P dose by about 25 per cent. The VAM inoculation coupled with fertilizer P, improved root colonization by and per cent, respectively covering first and second year of experimentation. In general, root colonization was higher with application of 50 per cent of P dose as compared to use of VAM culture alone. But, further increase in applied P to 75 per cent dose, reduced root infectivity with VAM. In a P deficient acid Alfisol, under wet temperate condition, combined application of 75 per cent of soil test base P dose and VAM culture gave yield statistically similar to 100 per cent P (STB) application. However, treatment 75 per cent P (STB) + VAM culture, increased grain and straw yields of wheat by 16 and 15 per cent, respectively over absolute control. Further, VAM inoculation along with fertilizer P application improved root colonization by per cent (Suri et al a ). Kongpun et al. (2011) conducted a field experiment with cowpea involving an acid soil categorized as low in available P. Results revealed that application of 64 kg

39 19 P 2 O 5 ha -1 along with VAM inoculation gave significantly higher (25%) dry matter yield over 32 kg P 2 O 5 ha -1 + VAM culture treatment. However, above treatment was found to be statistically at par with treatment involving VAM inoculation in the presence of 48 kg P 2 O 5 ha -1. In a field study conducted under wet temperate situation involving an acid Alfisol, Suri et al. (2011) reported that treatments, VAM inoculation + 75 per cent of P dose (STB) and 100 per cent P dose based on above concept, were found to be statistically alike in respect of grain/ seed yield. It can be inferred from above that soil test based (STCR concept) fertilizer P dose can be reduced by 25 per cent in wheat through the use of VAM biofertilizer. In another field experiment with soybean, conducted under similar soil and climatic conditions, above workers found that application of 100 per cent P dose based on soil test, gave 54 per cent higher yield over absolute control. However, above treatment was found to be statistically at par with 75 per cent P (STB) + VAM inoculation treatment. Further, treatment involving 75 per cent of P (STB) and VAM inoculation increased N, P and K uptake by 49, 92 and 60 per cent, respectively over control (Suri et al b ). ii. Soil properties The VAM fungi develop an extensive extra-radical hyphal network that grows away from the root, through the rhizosphere and into the surrounding bulk soil matrix. Above network makes a significant contribution to improvement of soil texture and water relations (Tisdall and Oades 1982; Miller and Jastrow 1990; Tisdall 1991). The extraradical hyphae of above fungi have been shown to be more important than root length and/ or bacterial populations in stabilizing soil aggregates (Schreiner et al. 1997). A number of workers have reported improvement in soil structure following VAM inoculation. The VAM inoculation resulted in improvement in soil structure by way of binding of soil aggregates, involving their hyphal network and in turn, enhancing soil moisture retention capacity (Tisdall 1991; Staddon et al. 2003; Hamblin 1985; Rilling 2004). Further, hyphae of mycorrhizal fungi produce a glycoprotein called glomalin which is capable of binding soil particles leading to aggregate formation and in turn, improve soil structure/ soil moisture retention capacity (Wright and Upadhyaya

40 ; Wright et al. 1998). Auge et al. (2006) reported that VAM fungi also improved soil structure indirectly, by enhancing root biomass, root length, root surface area and root volume density. Singh et al. (2009) conducted an experiment on green gram under temperate condition, involving a silty clay loam soil rating low in available P. Results revealed that combined application of 60 kg P 2 O 5 ha -1, 60 kg N ha -1 and VAM culture gave respective increases of 37, 7 and 5 per cent in soil available N, P and K status after harvest. In a field experiment, conducted on an acid Alfisol covering two years, Kumar (2010) reported that application of VAM + P 75 per cent (STB) gave respective increases of 6, 72 and 4 per cent in available N, P and K status in soil than control i.e. no application of P. The build-up in DTPA extractable micronutrients viz. Fe, Zn and Cu in above treatment was to the tune of 14, 30 and 9 per cent over control. Some workers conducted a field experiment with French bean involving a sandy loam soil rating low in available P. Results revealed that integrated application of 75 per cent of recommended dose of fertilizer (RDF), VAM 2 kg ha 1 and PSB 2.5 kg ha 1 gave respective increases of 8, 16 and 10 per cent in soil available N, P and K status over control (N 0 P 0 K 0 ). However, above treatment did not influence NPK status significantly over sole application of 100 per cent RDF (Ramana et al. 2010). Bhardwaj et al. (2010) studied the effect of conjoint use of inorganic fertilizers and organics on soil fertility under mid hills condition of Himachal Pradesh. Integrated use of 75 per cent RDF, VAM and Rhizobium gave a nominal build-up in soil organic carbon, available N, P, and K in soil after tomato and French bean harvest over applications of 100 per cent generalized recommended dose of NPK. However, both the above treatments were found to be statistically on par with one another, indicating a saving of 25 per cent of chemical fertilizers. Chaudhary et al. (2011) in an experiment on integrated nutrient management with groundnut, under semi-arid condition, found that application of 50 kg P 2 O 5 ha -1 + VAM gave significantly higher available N (164 kg ha 1 ) and available P (27 kg ha 1 ) in soil over control (P 0 ). The minimum values of above nutrients were recorded under application of 100 per cent recommended dose of P only. The findings of a field experiment, conducted by Suri et al. (2011) with wheat in a P deficient acid Alfisol of wet temperate region reported that VAM cultures alone or in

41 21 combination with increasing P levels from 50 to 75 per cent of P dose, resulted in a reduction in DTPA extratable micronutrient (Fe, Zn, Cu and Mn) contents over control and initial soil fertility status. However, micronutrient contents were relatively higher in VAM inoculated plots alone or in combination with 50 to 75 per cent P dose over sole application of 100 per cent P dose. Above findings suggest a positive role of VAM in nutrient mobilization and nutrient dynamics in soil plant system. There was a significant improvement in available N and P status in soil with VAM inoculation coupled with increasing P levels between 50 to 75 per cent of P dose, even though, highest P build-up was obtained with sole application of 100 per cent P dose. In another study conducted under above soil and climatic conditions involving maize crop, Suri et al. (2011) reported that treatment 75 per cent of soil test based recommended P + VAM inoculation led to build-up of available N, P and K status of soil by 16, 50 and 22 per cent, respectively over control (P 0 ). It is concluded from above that application of VAM, P and irrigation alone or in combination improved soil aggregation, water holding capacity, available soil nutrient status, nutrient uptake, crop growth, yield and quality significantly. 2.5 Influence of VAM and P application on the status of different forms of P in soils Soil phosphorus transformations depend upon soil type and management practices. In acid soils, there is an acute deficiency of phosphorus and it is most severe yield limiting nutrient for crop production. Most of the phosphorus added through chemical fertilizers, gradually reacts with Fe and Al compounds in acid soils and gets transformed in to relatively insoluble compounds. With time, solubility of these compounds decreases, resulting in P-fixation. Phosphate applied as water-soluble P source does not remain in the soil for a long period and quickly starts getting converted into sparingly soluble or insoluble P compounds. The transformation of applied P greatly depends on physical and chemical behaviour of soils. The VAM fungi are capable of mineralizing organic-p and solublizing inorganic- P in soils. Zou et al. (1995) attributed higher build-up of water soluble-p and inorganic-p

42 22 fractions in VAM treated plots to ability of VAM fungi to solublise inorganic forms of P by releasing low molecular weight organic acids (oxalic, mallic acid, etc.), which dissolve insoluble phosphates involving Fe and Al, rendering them soluble and available for use by plants. Further, above compounds solubilise insoluble phosphates by lowering soil ph, causing chelation of Fe and Al cations and competing with phosphate ions for adsorption sites on soil exchange complex, thereby, becoming available for release into soil solution for plant use (Nahas 1996). As per Chen et al. (2007), VAM fungi have the ability to mineralise organic-p in soils. Actually, this was facilitated by a high amount of release of organic acids and various enzymes. Fungal hyphae released enzymes (phosphatase, chitinase, peroxidase, cellulose and protease) which penetrated and digested substrates. Secretion of enzymes might have disintegrated complex organic substrates which could be then absorbed and utilized by VAM fungi and or host plants as energy and nutrient sources for growth and reproduction. Tarafdar and Claassen (1988) reported that phosphatase enzyme released by mycorrhizal fungi in the rhizosphere might promote acquisition of P by plants through hydrolysis of organic-p. The organic acids released by mycorrhizal hyphae may mobilise both organic and inorganic phosphorus from sparingly soluble Ca-P, Fe-P or Al-P in soil and enhance the availability of organic P for enzymatic hydrolysis (Gahoonia and Nielsen 1992; Fox 1995). Tarafdar and Marschner (1994) while working on semi-arid soils of tropical climate felt that phosphates enzyme released by mycorrhizal fungi in the rhizosphere may help in acquisition of P through hydrolysis of organic-p. They further found a higher Al- P status in mycorrhizal plots as compared to treatments involving no VAM biofertilizer. Mycorrhizal fungi release significant quantities of low molecular weight organic acids which dissolve less soluble phosphates such as Fe-P, Al-P and Ca-P by chelation with high efficiency (Fox and Comeford 1990). Patel et al. (1992) in a long term experiment evaluated the influence of P levels and organic manure on phosphorus availability and its fractions in calcareous soils. Results revealed that water soluble-p and Al-P decreased with time, but the reverse was

43 23 true in case of Fe-P and Ca-P. Organic manure incorporation increased significantly, contents of occluded-p, organic-p and available P in soil. Zhang and Mackenzie (1997) studied changes in P fractions under continuous cultivation with and without P fertilization. A higher annual application of 132 kg P 2 O 5 ha 1 increased soil Pi ( soil inorganic P) through NaHCO 3 -Pi, NaOH-Pi, and stable Cabound Pi (HCl-Pi) but, in case of Po (soil organic P), labile NaHCO 3 -Po fractions increased, while, labile NaOH-Po moderately decreased resulting in increased total extractable soil organic P (Po). Inoculation of arhar (legume crop) with VAM fungi showed that above fungi mobilized a good amount of P from both soluble and insoluble sources, thereby increasing yield and uptake of P by crop (Misra and Pattanayak 1997). Verma (2002) evaluated the effect of chemical fertilizers and amendments on phosphorus dynamics in a long-term fertilizer experiment on an acid Alfisol under temperate situation. Available P status increased under treatments involving fertilizer P and other amendments like lime over control and plots receiving only N fertilization. He found that, there was a significant increase in Al-P, Fe-P, Ca-P and residual P forms with application of inorganic fertilizers along with amendments like FYM and Zn application. Further, after continuous cropping and fertilization for 29 years, there were 44 and 11 per cent increase in available P, under 150 per cent NPK and 100 per cent NPK + FYM treatment, respectively over 100 per cent NPK application alone. Olsen s-p was positively and significantly correlated with all the fractions except H 2 O-P. The highest value of coefficient of correlation was observed with NaHCO 3 -P i indicating maximum correlation of available P with this fraction. Further, P uptake was correlated positively and significantly to NaHCO 3 -P i, NaOH-P o and available P in case of grain and stover yields. In another long term fertilizer experiment with soybean-wheat on a Vertisol, Tiwari et al. (2002) found a significant increase in available P status in treatments receiving 100 per cent of P dose (GRD). Sharma (2004) reported that NaHCO 3 -Pi is the most important chemical pool of P contributing to nutrition of maize and wheat grown in a sequence under acid Alfisol of Western Himalayas.

44 24 Verma et al. (2005) in a long-term fertilizer experiment on an acid Alfisol and temperate situation reported that integrated application of nutrients resulted in significantly lower P adsorption capacity of soils. At the beginning of experiment, various pools could be quantitatively ranked in the following order: residual-p> NaOH- Po> NaOH-Pi> NaHCO 3 -P 0 > NaHCO 3 -P i > HCl-P>H 2 O-P. As a result of continued P fertilization and cropping, the order changed as follows: residual-p> NaOH-Pi> NaOH- Po> NaHCO 3 -P i > NaHCO 3 -P 0 > HCl-P> H 2 O-P. Sihag et al. (2005) reported that, the amount of P recovered as saloid-p, Al-P and Ca-P increased significantly and magnitude of increase with inorganic fertilizer treatments, was more in the presence of organic material than in its absence. Among organic amendments, highest amount of all the forms of P was recorded under FYM followed by green manuring and press mud treatments. Talashilkar et al. (2006) found that Fe-P and Al-P exhibited a reduction in slightly acidic soils than in very strongly acidic ones, whereas, all other P fractions were increased with rise in soil ph. In a sandy loam Typic Haplustept (ph 8.2), Setia and Sharma (2007) reported that application of P increased all the P forms, whereas, N and K application caused a decrease in P fractions. Mishra et al. (2008) studied the influence of continuous application of amendments to maize-wheat cropping system on dynamics of soil microbial biomass in Alfisol of Jharkhand. Results revealed that relative abundance of inorganic P fractions was in the order of saloid-p < Fe-P < Al-P < Ca-P. The various inorganic P fractions tended to decline with crop age. A significant build-up of available P in soil receiving NPK alone or in combination with FYM was reported every year over control. It is concluded from above survey of literature that inoculation with VAM culture transformed organic and inorganic phosphorus pools leading to enhanced availability of phosphorus for plants, by way of enriching the labile-p pool/ P mineralization from organic matter. Further, INM practices influenced significantly the various forms of P in soil and prevent their adsorption on soil colloids. Inorganic pools are considered to be most important from crop nutrition point of view because of their rapid availability. Based on above account, planned study appears to be highly relevant to Palam Valley due to acidic nature of soils (ph 5.2), wet temperate climatic condition and high but, erratic rainfall (2500 mm).

45 25 3. MATERIALS AND METHODS The present study was carried out at the Experimental Farm of the Department of Soil Science, CSK Himachal Pradesh Agricultural University, Palampur (HP) - India during with the broad aim of assessing P and rain-harvested water economy through the integrated application of VAM, phosphorus and irrigation in okra-pea sequence. The experimental site is characterized as mid hills wet temperate zone of Himachal Pradesh. Above zone extends from 1000 to 1500 metres above mean sea level. The climate is usually wet temperate, annual temperature varying between C with average rainfall of 1500 mm. It comprises parts of seven districts of Himachal Pradesh viz. Kangra, Shimla, Mandi, Kullu, Solan, Chamba and Sirmour. The soils involved are predominantly loamy, clayey and silty clay loam in texture. These are shallow and have low water retentivity. Further, the soils are mostly acidic in nature, which are deficient in N and P. The major crops grown in the region are mainly wheat, paddy, maize, potato, oilseeds and pulses. Besides, Himachal Pradesh, above zone also exists in other states of the country viz. Jammu and Kashmir, Uttarakhand, Meghalaya, etc. The agroclimatic zone map of H.P. indicating the zone of current study is given as Fig The experimental site is located at 32º 6 N latitude and 76º3 E longitude at an elevation of 1250 m above mean sea level and is characterized as under mid hills wet temperate zone of Himachal Pradesh. The climate of the experimental area is characterized as wet temperate with mild summers (March to June) and cold winters (December to March). The annual rainfall received during and during was 1514 and 2438 mm, respectively. The rainfall received during Kharif (wet season) 2009 and Kharif 2010 was 1274 and 2076 mm, respectively. The rainfall received during Rabi (dry season) and Rabi was 240 and 362 mm, respectively (Fig. (s) 2 & 3 and Appendix-1 & 2). Further, information pertaining weekly rainfall, evaporation and temperature (maximum and minimum) for the crop periods are depicted in Figure (s) 3.2 and 3.3 and presented in Appendices- 1 and 2. The experimental field was silty clay

46 26 loam in texture belonging to order Alfisol classified as Typic Hapludalf (Verma 1979). The soil of experimental site was subjected to estimation of various soil physical and chemical parameters before the commencement of experiment, the detail of which are given in Table 3.1. Table 3.1 Important physical and chemical properties of experimental soil (0-15 cm) at initiation of experiment S.No. Parameter Status/ Value 1. Bulk density (Mg m -3 ) Mechanical separates (%) i. Sand 28.9 ii. Silt 47.2 iii. Clay 23.1 Textural class 3. Soil chemical properties Silty clay loam i. Soil reaction (ph) 5.1 ii. Organic carbon (g kg -1 ) 7.9 iii. Available nutrients (kg ha -1 ) N 190 P 19 K 105 iv. Exchangeable cations [c mol (p + ) kg -1 ] Ca 5.27 Mg 1.27 v. DTPA extractable micronutrients (mg kg -1 ) Fe 43.1 Mn 22.3 Zn 1.36 Cu 0.72 vi. Hot water soluble B (mg kg -1 ) 0.51 vii. Available Mo (mg kg -1 ) 0.12

47 27 Zone of study (Mid hills wet temperate zone) Fig 3.1 Agroclimatic zone map of H.P. (India), showing the zone of study (wet temperate zone)

48 Fig. 3.2 Mean weekly weather data at Palampur during (June 2009 to May 2010) 28

49 Fig. 3.3 Mean weekly weather data at Palampur during (June 2010 to May 2011) 29

50 Experimental detail The field experiment consisted of 14 treatments replicated thrice in randomized block design. The detail of treatments is described hereunder: Detail of treatments evaluated in okra (variety: P- 8) during Kharif and Kharif 2010 Treatment No. Treatment detail Treatment code T 1 55 kg P 2 O 5 ha -1 + Irrigation as per need and soil moisture content (Generalized nutrient recommended dose and generalized irrigation) V 0 100%NPK FYM 6.4t I AR (GRD) T 2 19 kg N ha -1 + Irrigation now and then depending on water availability (Farmers practice) V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 28 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC** V 0 P 50% I 40% T 4 41 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 0 P 75% I 40% T 5 55 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 0 P 100% I 40% T 6 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 50% I 40% T 7 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 75% I 40% T 8 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 100% I 40% T 9 28 kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 50% I 80% T kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 75% I 80% T kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 100% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 50% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 75% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 100% I 80% Treatment N (kg ha -1 ) K 2O (kg ha -1 ) T T T 3 T during 2009 & 55 during 2010 * AWC: Available water holding capacity (%); FYM: 2.5t fresh weight ha -1 or say 1.6 t ha -1 dry weight was applied in 13 treatments T 2 T 14 whereas, in T 1 FYM applied was 10 t fresh weight ha -1 or say 6.4 tha -1 on dry weight basis; AR: as per water requirement, WA: as per water availability. 1 Kharif (wet) season: The season that started from June/ July and ended in September/ October

51 Plate 3.1. A view of experimental okra crop during

52 Detail of treatments evaluated in pea (variety: Palam Priya) during Rabi and Rabi Treatment No. Treatment detail Treatment code T 1 60 kg P 2 O 5 ha -1 + Irrigation as per need and soil moisture content (Generalized nutrient recommended dose and generalized irrigation) V 0 100%NPK FYM 12.6t I AR (GRD) T kg N ha -1 + Irrigation now and then depending on water availability (Farmers practice) V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 30 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC* V 0 P 50% I 40% T 4 45 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 0 P 75% I 40% T 5 60 kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 0 P 100% I 40% T 6 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 50% I 40% T 7 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 75% I 40% T 8 12 kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 40% of AWC V 12 P 100% I 40% T 9 30 kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 50% I 80% T kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 75% I 80% T kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 0 P 100% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 50% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 75% I 80% T kg VAM ha kg P 2 O 5 ha -1 + Irrigation at 80% of AWC V 12 P 100% I 80% Treatment N (kg ha -1 ) K 2 O (kg ha -1 ) T T T 3 T FYM: 5t fresh weight ha -1 or say 3.1 tha -1 dry weight was applied in 13 treatments T 2 T 14 whereas, in T 1 FYM applied was 20 t fresh weight ha -1 or say 12.6 t ha -1 on dry weight basis 1 Rabi season: The season that started from October/ November and ended in March/ April

53 Plate 3.2. A view of experimental pea crop during

54 Lay out and treatment procedures The field experiment consisted of 14 treatments replicated thrice in a complete randomized block design (RBD). The size of each plot was 8m 2. Field preparation, lay out and leveling of individual plots were carried out in succession by employing manual labour. Treatments were allocated randomly to individual plots, concentrating on a single replication at a time. The FYM and macronutrients viz. nitrogen, phosphorus and potassium were applied in different plots, respectively as urea, single super phosphate and muriate of potash, their amounts varying depending on the treatments. Mycorrhizal biofertilizer (VAM) culture used in the experiment belonged to Glomus mosseae L. and it was obtained from Division of Microbiology, Indian Agricultural Research Institute (IARI), New Delhi (India). Mycorrhizal biofertilizer (VAM) culture was applied by seed treatment method just prior (2 hours before) to sowing of okra and pea. The required amount of seeds were dipped in a well mixed slurry comprising of VAM culture, fertile soil and water in the ratio of 1:1:4, respectively for 30 minutes. A nominal amount of FYM (1/4 rths of recommonded) was incorporated in all plots except those having generalized recommended dose (T 1 ). The N, P and K fertilizer application in various plots was made on the basis of traditional soil test based approach i.e. grouping of soils into low, medium and high classes. The medium status values followed for above nutrients respectively were , and kg ha -1. As per the university (CSK HPKV, Palampur) package of practices, the medium fertility recommendations followed for N, P 2 O 5 & K 2 O were 75, 55 & 55 kg ha -1 in case of okra and 50, 60 & 60 kg ha -1 for pea. If the nutrient rating above happened to be high in case of N/P/K, respective recommended dose mentioned above was reduced by 25 per cent. If the nutrient rating turned out to be low, the respective recommended doses given above were increased by 25 per cent. For irrigation scheduling, Soil moisture regime approach i.e. Gravimetric method (Hillel 1982) was adopted. Above approach involved determination of soil moisture content and irrigation at pre-fixed moisture contents i.e. a) 80% of AWC i.e. at 23.8% b) 40% of AWC i.e. at 21.6%). For the purpose, the soil samples (0-15 cm) were collected in moisture boxes from individual plots regularly; the same were then dried in

55 35 oven at 105 o C for 24 hours. Using the fresh weight and oven dry weights recorded, relevant moisture contents were worked out. Upon the arrival of predetermined moisture status, the irrigation (5 cm depth) was applied in concerned plots. 3.3 Field operations The field used for raising okra and pea crops was ploughed twice, followed by planking. In okra, the row to row distance of 50 cm and plant to plant distance of 15 cm was maintained. In pea, the distances maintained were 50 cm and 7.5 cm, respectively. The half dose of N and full doses of P and K were placed at the time of sowing of both the crops. The remaining half of N was top dressed in two equal splits viz. after one month of sowing and just before flowering in okra and pea. The fertilizers, manure and VAM culture were applied as per the treatments scheduled in various plots. Irrigations (5 cm each) were applied by pipe irrigation method based on soil moisture content. In order to manage weeds, spraying with 4 litre ha -1 was followed after sowing (with in 48 hrs) of both the crops. All required operations were carried out as per standard agronomic practices recommended for individual crops by the university (Anonymous 2012). The schedule followed for the various agronomic operations is given in Table.3.2. Table 3.2 Schedule of various agronomic operations in okra and pea S. No. Operation Okra Pea Seed Inoculation with VAM culture June 8 May 27 November 3 October Sowing June 8 May 27 November 3 October Fertilizer application June 8 May 27 November 3 October Interculture July 10 & August 2 July 3 & July 28 December 4 December 4 5. First picking August 14 August 8 March 16 March Final picking and harvesting of stover October 3 September 24 April 6 April 4

56 Analytical work involving VAM culture, FYM and experimental soil VAM spore count Above property is a measure of potential of VAM culture to infect the crop host concerned. Above parameter was determined by the method given by Gaur and Adholeya (1994). Weighed out 10 g of VAM culture into a 100 ml glass beaker, stirred the suspension with glass rod and kept it for 15 minutes after which a drop of suspension was collected, spread over the slide and observed under compound microscope at 40X magnification. The VAM spores were counted and recorded as number g -1 of culture. The spore count was found to be g -1 culture Farm yard manure (FYM) Total N, P, K and micronutrients were determined employing standard methods (presented later in Table 3.4). The relevant information is presented in Table 3.3. Table 3.3 Composition of FYM used in experiment S. No. Parameter Okra Pea Moisture (%) Nitrogen (%) Phosphorus (%) Potassium (%) Calcium (%) Magnesium (%) Zinc (mg kg -1 ) Iron (mg kg -1 ) Manganese (mg kg -1 ) Copper (mg kg -1 ) Boron (mg kg -1 )

57 Experimental soil Representative soil samples (0-15 cm depth) were collected from each plot before sowing and after harvest of each crop. The soil samples were dried in shade, ground in wooden pestle mortar, passed through 2 mm sieve and analyzed for various chemical properties by using standard methods given in Table 3.4. Table 3.4 Analytical methods employed in soil chemical analysis S.No. Parameter Method employed 1. Soil reaction (ph) 1:2.5 soil : water suspension (Jackson 1967) 2. Organic carbon (g kg -1 Rapid titration method (Walkley and ) Black 1934) 3. Available nutrients (kg ha -1 ) N P K 4. Exchangeable cations [c mol (p + ) kg -1 ] Ca Mg 5. DTPA extractable micronutrients (mg kg -1 ) Fe Mn Zn Alkaline permanganate method (Subbiah and Asija 1956) 0.5 M NaHCO 3, ph=8.5 (Olsen et al. 1954) Neutral ammonium acetate (Black 1965) Neutral normal NH 4 OAc extraction Method (Merwin and Peach 1951) DTPA method (Lindsay and Norvell 1969) Cu 6. Hot water soluble B (mg kg -1 Carmine method (Hatcher and Wilcox ) 1950) 7. Available Mo (mg kg -1 Ammonium oxalate method (Grigg ) 1953) Different forms of phosphorus i.e. P 8. fractions (mg kg -1 ) Sui et al. (1999)

58 Soil physical properties Soil samples were collected from 0-15 cm depth for the determination of soil physical properties (aggregate analysis, bulk density, particle density, water holding capacity and available water range) and from 0-15, and cm depths for the estimation of soil moisture content. The various techniques followed for estimation of soil physical properties are as under: S.No. Parameter Method employed 1. Mechanical separates (%) International pipette method (Piper 1950) 2. Soil water content (%) Gravimetric method (Hillel 1982) 3. Soil aggregate analysis (mm) Yoder s Apparatus (Yoder 1936) 4. Bulk density (Mg m -3 ) Core method (Singh 1980) 5. Water holding capacity (%) Keen s box method (Piper 1950) Available water capacity (AWC)/ Available water range (%) Moisture contents at field capacity (FC) and permanent wilting point (PWP) in the experimental soil (0-15 cm depth) were determined by using pressure plate apparatus (Hillel 1982). Available water range was calculated by deducting moisture content pertaining PWP from FC moisture content. The FC signifies soil moisture retained at -33 k Pa matric potential and PWP signifies soil moisture retained at k Pa matric potential. In current study, values of FC and PWP found are given hereunder: FC (%) = 26.. (1) PWP (%) = (2) AWC (%) (1-2) = 11 Irrigation at 80 per cent of AWC means: applying irrigation when moisture content in soil reaches 23.8 per cent. Irrigation at 40 per cent of AWC means: applying irrigation when moisture content in soil reaches 21.6 per cent.

59 Observations Growth observations In each plot, five okra/ pea plants were selected randomly, which were tagged and used for recording growth parameters periodically. i. Plant height (cm) Above parameter was measured twice (60 & 100 DAS) during crop growth using a metre scale, from ground level to tip of the tallest leaf in extended position. ii. Dry matter accumulation (g plant -1 ) The dry matter accumulation was recorded twice (60 & 100 DAS) during crop growth period. The studies were concentrated on one replication only. The two randomly selected plants were removed from each plot. Above plant samples were dried in an oven at 60 o C for 72 hours and their weights were recorded. The average weight of above two plants was expressed as dry matter accumulation. iii. Leaf area index (LAI) Above parameter is the ratio of total leaf surface of a plant divided by surface area of the land on which plant grows. Two plants of okra/ pea from central two rows were selected at random twice (60 & 100 DAS) during crop growth and removed for periodic measurement of leaf area index. First of all, area of total number of leaves per plant was measured on leaf area meter. The LAI was calculated by the formula given by Redford (1967) as: LAI = Leaf area (m 2 ) Ground area / spacing of crop (m 2 ) Ground area = row to row distance x plant to plant distance Spacing of okra= 0.50 m x 0.15 m; spacing of pea= 0.50 m x m 3.7 Plant water studies Xylem water potential (k Pa) Above parameter indicates energy status of plant water. This parameter was determined in the field on standing crop using pressure bomb apparatus at 60 and 100

60 40 DAS (Waring and Cleary 1967). From each plot, a fully exposed leaf from middle of the plant along with petiole was selected. The leaf was subjected to gradual pressure till the sap oozed out from the leaf petiole. The pressure at the point of oozing out of sap was recorded. The same method was used for other plants. The observations were taken at 0700 hours (morning) and 1400 hours (after noon) Relative leaf water content (%) Relative leaf water content (RLWC) indicates the moisture status of plants. Five leaves were sampled from each plot. These were brought to the laboratory in tightly closed polythene begs and then fresh weights were recorded. Now, these leaves were chopped into 0.5 cm pieces and saturated over night in petri plates. The saturated leaves were taken out the next day, dried between the folds of a filter paper followed by recording of their turgid weight. The same were now transferred to an oven for 72 hours after which their weight was taken. RLWC was computed from the fresh weight, turgid weight and oven dry weight according to the method given by Weatherly (1950) as: RLWC (%) = Fresh weight Oven dry weight Fully turgid weight Oven dry weight x Water use efficiency The above parameter was worked out with the objective of assessing the irrigation water economy through various treatments in the experiment. It was computed by the using the following formula. Water use efficiency (WUE) was worked out (Reddy and Reddi 2002). WUE (kg ha -1 mm -1 ) = Yield (kg ha -1 ) Total amount of water used (ha-mm) Total water used was calculated by taking into consideration the total number of irrigations applied and effective rainfall during crop growth.

61 Root studies Above studies were carried out at the maximum flowering stage of both the crops. The studies were concentrated on one replication only. The root samples were taken from 0-30 cm depth by Core break method (Bohm 1979). In present study, a metallic core of 10.3 cm internal diameter and 13.4 cm height was used. The soil samples with root mass were kept in water over night and then, roots were made free from soil by gentle washing with a fine jet of water. The roots were collected on sieves and observations on following parameters were made: Maximum root length (cm) The fresh root samples belonging to different treatments were placed on a hard sheet in stretched condition followed by measurements of their maximum lengths using a metre scale Root volume (ml) Root volume was determined by displacement method given by Mishra and Ahmed (1987). About 500 ml of water was poured into a 1000 ml measuring cylinder and roots belonging to the given treatment were transferred to it and change in water volume reading were recorded Root weight (g) Root samples collected earlier were dried in an oven at 65 o C for 24 hours and their dry weights were recorded Root weight density (g m -3 ) Above parameter is a function of root dry weight and actual root volume i.e. the soil volume from which the roots were collected (1.16 m 3 ) and measured. This was obtained as ratio between the weight of dry roots and the volume of soil (i.e. volume of sampling core) from which these were sampled (Mishra and Ahmed 1987) VAM colonization study Above study was carried out by the method given by Phillips and Hayman (1970). Above method consists of seven steps which are described below.

62 42 i. Harvested roots were subjected to repeated washing in tap water, chopped into 1 cm segments/ bits and placed in 10% KOH solution, approximately for 5 minutes. ii. iii. iv. The roots were now rinsed with tap water followed by their treatment with 1 N HCl solution for 5 minutes. Roots were placed in 0.05 per cent trypan blue (dissolved in lectophenol solution) for 5 minutes. Destaining of roots was done by using 50 per cent glycerol solution. v. Root segments were examined under compound microscope at 40 X magnification. vi. vii. Total numbers (s) of segments colonized were observed followed by computation of per cent colonization. Using above data, per cent root colonization was worked out following formula: Mycorrhizal colonization (%) = Number of root bits infected Total no. of root bits examined x Yield and yield contributing characters Besides yield, various yield contributing characters which were observed during experiment include fruit/ pod length, fruit/ pod girth, fruit/ pod number per kg and average fruit/ pod weight. The yield was duly recorded at every picking in both the crops. Out of various pickings; yield contributing characters were measured at alternate pickings i.e. thrice in okra and twice in pea Fruit / green pod yield (q ha -1 ) The number of fruits / green pods at each picking was weighed and summed up to get the total fruit / pod yield Fruit / pod length (cm) Fruit/ pod length of five randomly sampled fresh fruits/ pods was measured with a scale and average values were worked out for each treatment.

63 Fruit / pod girth (cm) Besides length measurement, three representative fruits/ pods selected above from each plot were subjected to girth (maximum girth from the middle of fruit/ pod) measurement (cm). It was expressed as mean fruit / pod girth for each treatment Average fruit / pod weight (g) Average fruit / pod weight was calculated by dividing the total fruit weight with total number of fruits obtained in each individual treatment Laboratory analysis Plant analysis Plant samples (leaves and pods) collected at final picking from all the field plots, were air dried and then dried in an oven at 60 o C for 72 hours. The dried samples were now ground in a Willey Mill fitted with stainless steel parts, and passed through 1 mm sieve and stored in paper bags for analysis. The analytical procedures for the estimation of various nutrients in plant and manure samples are given in Table 3.5 (AOAC 1970). Table 3.5 Analytical methods employed in plant and manure analysis S.No. Parameter Method employed Reference 1. Nitrogen Micro-Kjeldahl method Piper (1950) 2. Phosphorus Vanado-molybdo-phosphoric Piper (1950) acid yellow colour method 3. Potassium Wet Digestion method Piper (1950) 4. Fe, Mn, Zn and Cu Wet Digestion method Jackson (1967) 5. Boron Carmine method (Hatcher and Wilcox 1950) 6. Molybdenum Grigg s method Grigg (1953)

64 Quality parameters The quality parameters mainly Ca, Fe and crude protein contents were determined in okra fruits and pea pods. Crude protein content of fruits/ pods from different treatments was determined by estimating their total N content (Jackson 1967). The total N values thus found were multiplied with a factor of 6.25 to obtain the crude protein content. The Fe and Ca contents in okra/ pea fruits and pods, respectively were extracted by wet digestion method (digestion with diacid, HNO 3 :HClO 4 ::9:4) and determined on atomic absorption spectrophotometer (Jackson 1967). The detail of sampling procedure followed for estimation of Fe and Ca in okra and pea is given under sub-head plant analysis Nutrient uptake studies The uptake of nutrients was determined by multiplying yield with nutrient concentration as follows: Nutrient Uptake (kg ha -1 ) = Per cent concentration of the nutrient x yield of the crop in q ha -1 (oven dry weight basis) Note: 1. Nutrient concentrations in okra fruit/ pea pod yields and stover are given in Appendix- 3, 4, 5, 6 and 7 2. Moisture contents (%) in okra fruits/ pea pods are given in Appendix Agronomic efficiency of P based on response ratio (kg yield kg -1 P) The efficiency of applied P nutrient in different treatments was estimated in the form of phosphorus response ratio (agronomic efficiency) by applying the following formula: Phosphorus response ratio (kg yield kg -1 P) = Yield in treated plot (kg ha -1 ) - Yield in Farmers practice plot (kg ha -1 ) P applied as P 2 O 5 (kg ha -1 ) As there was no absolute control treatment in the experiment, the one closest to it i.e. the farmers practice was utilised to assess above parameter.

65 Statistical analysis All the field and laboratory data were analyzed statistically by the methods described by Gomez and Gomez (1984) through the requisite statistical computations to predict the cause and effect relationship of various treatments with the productivity of okra-pea and nutrient uptake. Further, data of the two individual years were analysed for homogeneity using F-test. The data found homogeneous were further subjected to pooled analysis. The correlations were computed by using formula of Robinson et al. (1951). To test the significance of these correlations coefficients, r values obtained were compared against correlation coefficient values in Fisher and Yates tables (1958) at 5 per cent level of significance Meteorological parameters The data for rainfall, evaporation, temperature (maximum and minimum) and relative humidity were procured from the meteorological observatory of the Department of Agronomy, CSK Himachal Pradesh Agricultural University, Palampur Economic analysis The economic analysis of the experiment was carried out by taking into consideration the prevailing prices of inputs used and okra fruits and pea pods. The various over head costs such as that on seed bed preparation, input costs, seed treatment, plant protection, etc. have also been taken into account. Fruit and pod yield of okra and pea, respectively were also taken into account for above purpose. Above exercise has been executed in two ways i.e. i. Analysis of individual okra and pea crops covering two years. The formulae used are given below: Gross returns (Rs. ha -1 ) = Yield (q ha -1 ) x price of produce (Rs. kg -1 ) Net returns (Rs. ha -1 ) = Gross returns (Rs. ha -1 ) - cost of cultivation (Rs. ha -1 ) Benefit cost ratio = Net returns (Rs. ha -1 ) Cost of cultivation (Rs. ha -1 )

66 46 ii. In order to have an idea of profitability of the entire okra-pea sequence covering two years, year wise analysis of above sequence as a whole. The various formulae used are given below: Pea equivalent yield (q ha -1 ) = Yield of pea (q ha -1 ) + [Price of okra (Rs. kg -1 ) x yield of okra (q ha -1 )] Price of pea (Rs. kg -1 ) x 100 Gross returns (Rs. ha -1 ) = Pea equivalent yield (q ha -1 ) x Price of pea (Rs. kg -1 ) Net returns (Rs. ha -1 ) = Gross returns (Rs. ha -1 ) - [(cost of cultivation of pea (Rs. ha -1 ) + cost of cultivation of okra (Rs. ha -1 )] Benefit-cost ratio = Net returns (Rs. ha -1 ) [(cost of cultivation of pea (Rs. ha -1 ) + cost of cultivation of okra (Rs. ha -1 )]

67 47 4. RESULTS AND DISCUSSION Results which emerged from current study on okra-pea sequence are presented in this chapter under the heads given below: 4.1 Effect of integrated application of VAM, phosphorus and irrigation on okra 4.2 Effect of integrated application of VAM, phosphorus and irrigation on soil chemical properties after okra harvest 4.3 Economic analysis of experiment on okra 4.4 Effect of integrated application of VAM, phosphorus and irrigation on pea 4.5 Effect of integrated application of VAM, phosphorus and irrigation on soil chemical properties after pea harvest 4.6 Economic analysis of experiment on pea 4.7 Phosphorus transformation in soil as influenced by its application along with VAM and irrigation in okra-pea sequence 4.8 Soil physical properties as influenced by integrated application of VAM, phosphorus and irrigation after two years of investigation 4.9 Relationship between different P fractions and various plant and soil parameters belonging to okra and pea 4.10 Economic analysis of experiment on okra-pea sequence

68 Effect of integrated application of VAM, phosphorus and irrigation on okra Growth parameters i. Plant height In general, as a consequence of treatment application, there was a sharp increase in plant height during days period and beyond that, increase in plant height was to a relatively less extent till the crop matured. During 2009, at 50 days after sowing (DAS), highest plant height was recorded under V 0 100%NPK FYM 6.4t I AR / GRD followed by V 12 P 100% I 80% and V 12 P 75% I 80%, all of which were found to be statistically at par with one another (Fig. 1). Likewise, plant height given by V 12 P 100% I 40% and V 12 P 75% I 40% did not differ significantly than GRD. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. At 100 days of crop growth, maximum and significant increase in plant height was observed under GRD than V 12 P 100% I 80% and V 12 P 75% I 80%, respectively (Fig. 4.2). Similarly, increase in above parameter obtained under GRD was significantly higher over V 12 P 100% I 40% and V 12 P 75% I 40%, respectively. The treatment V 12 P 100% I 80% gave significantly higher (44%) plant height than V 0 P 100% I 80%. A similar trend was found in case of treatments involving irrigation at 40 per cent of AWC with and without VAM inoculation at varying levels of P. The farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ) was the lowest performing treatment. On the pattern of 2009, at 50 DAS, 2010, maximum and significant increase in above parameter was observed under V 0 100%NPK FYM 6.4t I AR / GRD than V 12 P 100% I 80% and V 12 P 75% I 80%, respectively (Fig. 4.3). Likewise, increase in above parameter obtained under GRD was significantly higher in comparison with V 12 P 100% I 40% and V 12 P 75% I 40%, respectively. The treatment V 12 P 100% I 80% gave significantly higher (5%) plant height as compared to V 0 P 100% I 80%. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P.

69 Plant height (cm) Plant height (cm) ,5 35,2 42,4 44,6 44,4 42,4 45,2 45,2 44, ,3 45,4 46,2 46, T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.37 Fig. 4.1 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 50 DAS during ,2 71,9 93,2 95,7 97,4 94,5 97,2 98, ,6 96,2 98,9 100,6100, T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 2.34 Fig. 4.2 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 100 DAS during 2009 Treatment detail appears on page 30

70 Plant height (cm) Plant height (cm) ,5 32,6 32,5 33,8 33,5 34,2 34,3 33,3 33, ,3 35,7 36, T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.31 Fig. 4.3 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 50 DAS during ,4 61,5 72,5 75,1 76,9 75,7 78,2 79,7 76,6 78,1 80,1 78,6 80,6 81, T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.32 Fig. 4.4 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of okra at 100 DAS during 2010 Treatment detail appears on page 30

71 51 At 100 days (during 2010), highest plant height was recorded under V 0 100%NPK FYM 6.4t I AR / GRD followed by V 12 P 100% I 80% and V 12 P 75% I 80%, all of which were found to be statistically alike (Fig. 4.4). Likewise, plant height given by V 12 P 100% I 40% did not differ significantly than GRD. Further, differences in above parameter between V 12 P 100% I 80% and V 0 P 100% I 80% were also observed to be nonsignificant. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. During the two years study, at the two stages, plant height given by treatments V 12 P 100% I 80% and V 12 P 100% I 40% did not differ significantly than their counterpart treatments involving same VAM and irrigation levels at 75 per cent of soil test based recommended P dose i.e. V 12 P 75% I 80% and V 12 P 75% I 40% treatments. It suggests an economy of about 25 per cent in soil test based fertilizer P dose. It suggests an economy of about 25 per cent in soil test based fertilizer P dose. A similar trend was found in case of treatments not involving VAM inoculation at varying levels of P and irrigation regimes. Overall, irrespective of VAM and irrigation levels, plant height increased with each additional increment of P dose. The P application at 100 per cent level gave 2 and 4 per cent higher, but non-significant plant height, respectively over 75 and 50 per cent of soil test based recommended P dose. Similarly, plant height given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. It is obvious that above treatments gave statistically similar performance at both the irrigation regimes. Above trend is obvious, as crop did not suffer due to moisture stress at important physiological stages viz. flowering and pod formation. The total rainfall was throughout more than adequate (1274 and 2076 mm during 1 st and 2 nd year, respectively) and the same was well-distributed. As such, effects due to irrigation regimes may be nonsignificant. The farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ) was the lowest performing treatment. The farmers of Palam Valley region apply only one fourths of recommended N and organic manure (FYM). Further, use of phosphatic and potassic fertilizers is almost nil. Besides above factors, very few farmers use biofertilizers. It reflects a great

72 52 technology gap in above region. The enhanced productivity observed under integrated application of VAM, P and irrigation reflects a huge potential to boost productivity and profitability of okra in an acid Alfisol of wet temperate zone of Western Himalayas. It is summarized that the highest plant height was observed in case of GRD than all other treatments. On the whole, GRD is superior in build-up of plant stand because, it involved a higher level of fertilizer nutrients (100 % NPK) along with 10 t FYM ha -1. However, in general, treatments involving VAM inoculation under different levels of P and irrigation regimes gave higher plant height than those without it. Further, effects due to P and irrigation regimes were observed to be non-significant. In contrast to VAM involving treatments, FYM at 6.2 t ha -1 on dry weight basis was applied in case of GRD, which improved the soil physical, chemical and biological properties thereby, boosting plant height. On the other hand, better growth of VAM inoculated okra plants over non-vam inoculated ones is attributable to exploration of larger volume of soil through mycelial growth of VAM, thereby enabling plant root system to absorb nutrients from deeper soil, thereby improving mineral absorption capabilities of plant roots, resulting in higher nutrient utilization. This was consequently reflected as enhanced plant growth of okra. Premsekhar and Rajashree (2009) have reported nominally higher (2%) height of okra plants with sole application of 20 t FYM ha -1 than application of 100 per cent generalized recommended dose of NPK in a neutral soil rating medium in available P under temperate condition, which is attributed to above reasons. A higher plant height of VAM inoculated plants over non-vam inoculated ones is attributable to exploration of plant roots thus, improving nutrient and water absorption resulting into more plant height. A similar trend has been reported by Bahadur and Manohar (2001) under similar conditions, who attributed the same to above reasons. ii. Leaf area index (LAI) It is apparent from Fig (s) 4.5 and 4.6 that LAI increased sharply in different treatments up to 100 days, after which, it became more or less constant. During 2009 and 2010, at 50 days, marginally higher LAI was observed under V 0 100%NPK FYM 6.4t I AR / GRD followed by V 12 P 100% I 80% and V 12 P 75% I 80%, all of which were found to be

73 Leaf area index Leaf area index 53 3,00 2,90 2,75 2,76 2,80 2,74 2,78 2,82 2,66 2,73 2,73 2,75 2,82 2,82 2,27 2,00 1,00 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.10 Fig. 4.5 Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 50 DAS during ,00 4,67 4,32 4,42 4,46 4,46 4,56 4,57 4,47 4,51 4,54 4,50 4,56 4,56 4,00 3,56 3,00 2,00 1,00 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.12 Fig. 4.6 Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 100 DAS during 2009 Treatment detail appears on page 30

74 54 followed by V 12 P 100% I 80% and V 12 P 75% I 80%, all of which were found to be statistically at par with one another (Fig. 4.5 and 4.7). The LAI given by V 12 P 100% I 40% did not differ significantly than GRD. Irrespective of P and irrigation regimes, treatments involving VAM inoculation gave statistically similar LAI than non-vam inoculated ones i.e. treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. A similar pattern of data in respect of above parameter was observed in treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM inoculation at varying levels of applied P. Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose did not differ significantly in respect of LAI than those involving 75 and 50 per cent of P dose during the two years of investigation (at both stages). But, LAI increased nominally with additional increment of P application. Irrespective of VAM and P levels, treatments involving irrigation at 80 per cent of AWC gave statistically similar LAI to those involving irrigation at 40 per cent of AWC i.e. between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 12 P 50% I 80% and V 12 P 50% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% gave statistically similar performance and were found to be non-significant. Therefore, differences due to irrigation may be non-significant. The same reasoning as given under plant height holds good here also. At 50 and 100 days, the farmers practice was found to be significantly inferior to all other treatments in respect of above parameter, during the two years of investigation. It is summarized that during 2009, highest LAI was observed under GRD than other treatments due to higher nutrient dose involved (100% NPK + FYM 6.4 t ha -1 on dry weight basis). However, during 2010, LAI was nominally higher in VAM inoculated treatments in comparison to GRD. It was attributable to build-up of VAM inoculum in soil after its continuous application. Because of lesser magnitude of root infection by VAM during first year of experimentation, there was a lower LAI value under treatment receiving VAM which increased greatly during second year, resulting into comparatively

75 Leaf area index Leaf area index 55 3,00 2,72 2,61 2,65 2,63 2,64 2,69 2,70 2,53 2,58 2,63 2,66 2,66 2,74 2,14 2,00 1,00 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.07 Fig. 4.7 Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 50 DAS during ,00 4,00 4,36 3,43 3,99 4,06 4,17 4,20 4,35 4,39 4,14 4,14 4,18 4,23 4,35 4,40 3,00 2,00 1,00 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.19 Fig. 4.8 Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of okra at 100 DAS during 2010 Treatment detail appears on page 30

76 56 higher or almost similar LAI under VAM involving treatments. Further, effects due to P and irrigation regimes were observed to be non-significant. As the literature on okra crop vis-à-vis integrated application of VAM, P and irrigation is scanty, reports from other vegetables and cereals have been cited here as required. The increased LAI values resulting from combined application of 100 per cent NPK and FYM 6.4 t ha -1 on dry weight basis are attributable to same reasoning as cited in case of plant height earlier. On the other hand, a better growth of VAM inoculated okra plants over the non-vam inoculated ones is attributable to enhanced activity of cytokinin (a growth promoter, of which P is a component), which promoted leaf growth by stimulating cell division and cell expansion. A similar explanation has also been given by Li et al. (1994). Results are in conformity with findings of Osonubi (1994), who reported significantly higher leaf area (18.4 m 2 plant -1 ) in VAM inoculated maize plants under temperate situation involving an Alfisol (ph 6.8). Edathil et al. (1996) have also reported higher (61%) leaf area of tomato due to combined application of VAM and P in P deficient soils under humid conditions. iii. Periodic dry matter accumulation Effect of integrated application of VAM, P and irrigation on okra is depicted in Fig (s) It is notable that at 50 DAS (2009 and 2010), various treatments did not affect dry matter accumulation significantly, barring farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ), which was found significantly inferior to all treatments (Fig. 4.9 and 4.11). At 100 DAS, during 2009, highest dry matter accumulation was found under V 12 P 100% I 80% followed by V 12 P 75% I 80% and V 12 P 100% I 40%, all of which were found to be statistically at par with one another (Fig. 4.10). Above treatments were also found to be statistically at par with V 0 100%NPK FYM 6.4 I AR / GRD. The treatments V 12 P 100% I 80% and V 12 P 50% I 80% gave significant increases of 6 and 9 per cent in above parameter, respectively than their non-vam counterparts involving same P and irrigation regimes i.e. V 0 P 100% I 80% and V 0 P 75% I 80%. Further, increase in above parameter was significantly higher (8%) under treatment V 12 P 75% I 40% in comparison with treatment involving same P and irrigation regime without VAM inoculation i.e. V 0 P 75% I 40%.

77 57 Dry matter accumulation (g plant -1 15,0 10,0 5,0 0,0 13,9 13,9 13,2 11,4 12,3 12,8 11,7 12,1 13,0 13,0 13,7 12,9 12,4 6,5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = NS Fig. 4.9 Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of okra at 50 DAS during 2009 Dry matter accumulation (g plant -1 45,0 40,0 35,0 30,0 25,0 20,0 15,0 10,0 5,0 0,0 40,4 35,6 37,7 39,6 40,6 41,0 37,6 36,0 37,6 39,2 41,1 41,6 37,0 23,4 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) 1.49 Fig Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of okra at 100 DAS during 2009 Treatment detail appears on page 30

78 58 During 2010 (at 100 DAS), highest dry matter accumulation was found under V 12 P 100% I 40% followed by V 12 P 100% I 80% and V 12 P 75% I 80%, all of which were found to be statistically similar (Fig 4.12). The values of above parameter given by above three treatments did not differ significantly than GRD. On the pattern of 2009, V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments gave significant increases of 4, 6 and 5 per cent in dry matter accumulation in okra, respectively than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, respective increases in above parameter given by V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% treatments were 5, 6 and 3 per cent, over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40% treatments. The differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% treatments in respect of above parameter were found to be non-significant. It signifies an economy of about 25 per cent in soil test based fertilizer P dose. However, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 12 and 9 per cent over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatments V 0 P 100% I 80% gave significant respective increases of 4 and 9 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 5 and 11 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. During 2010, treatment-wise trend with respect to above parameter was similar to that found during 2009 (Fig 4.10). During the two years of study, at 100 DAS, irrespective of VAM and P levels, values of dry matter accumulation given by treatments involving irrigation at 80 per cent of AWC, were found to be statistically similar to those involving irrigation at 40 per cent of AWC i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 12 P 50% I 80% and V 12 P 50% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also found to be non-significant. As such, effects due to irrigation regimes were found to be non-significant. The reasoning for above behaviour is the same as given under plant height. Overall, it can be deduced from above that VAM inoculated plants gave nominally higher (5%) dry matter accumulation as compared to non-vam inoculated ones. Further, P levels enhanced dry matter accumulation on an average by 8 per cent.

79 Dry matter accumulation (g plant -1 ) 59 Dry matter accumulation (g plant -1 15,0 10,0 5,0 0,0 12,0 11,0 11,2 11,3 11,4 12,0 12,3 11,3 11,5 11,6 11,7 12,1 12,5 5,6 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = NS Fig Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of okra at 50 DAS during ,0 35,0 34,3 31,8 32,9 33,7 32,8 35,0 35,4 32,0 33,1 34,1 33,5 35,1 35,3 30,0 25,0 20,0 20,6 15,0 10,0 5,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.14 Fig Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of okra at 100 DAS during 2010 Treatment detail appears on page 30

80 60 A higher amount of dry matter accumulation in VAM inoculated plants is attributable to more efficient absorption, utilization and assimilation of soil moisture. Above processes regulated stomatal openings and enhanced dry matter production. The above reasoning has been cited by Bethlenfalvay et al. (1988) for enhanced LAI in their studies. Davies and Linderman (1991) have attributed above increase, to improved water relations resulting from enhanced P nutrition. The results of the present study are in agreement with the findings of Kongpun et al. (2011), who observed 25 per cent higher dry matter production in cowpea under combined application 64 kg P 2 O 5 ha -1 and VAM inoculation over 32 kg P 2 O 5 ha -1 + VAM culture in a field experiment involving an acid soil categorized as low in available P Yield contributing characters and yields Yield contributing characters i. Fruit length Fruit length data as affected by various treatments are presented in Table 4.1. Most of the treatments had a favourable effect on fruit length at different pickings. At 2 nd picking, fruit length ranged from 12.7 to 15.0 and 12.7 to 14.7 cm under different treatments during 2009 and 2010, respectively. But, differences amongst various treatments were found to be non-significant excepting farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ), which happened to be significantly inferior to all other treatments, during both the years. Pooled analysis of data in respect of above parameter led to same trend as above. However, the highest and equal increase in above character was recorded under V 12 P 100% I 80%, V 12 P 100% I 40% and V 0 100%NPK FYM 6.4 I AR / GRD treatments, during the two years of study. It is obvious from data presented in Table 4.1 that at 5 th picking, trend of fruit length was similar to that under 2 nd picking stage. During 2009 (at 8 th picking), maximum, significant and equal increase (16% each) in above parameter was observed under V 12 P 100% I 80% and V 12 P 100% I 40%, respectively than GRD. The fruit length given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments was 18, 15 and 12 per cent higher, respectively than their non-vam counterparts involving

81 61 Table 4.1 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit length (cm) during crop growth 2 nd picking 5 th picking 8 th picking Treatment Pooled Pooled Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

82 62 the same P and irrigation regime i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. A similar trend of data was observed in treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM inoculation at varying levels of applied P (Table 4.1). Across all pickings, fruit length given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. The differences between treatments V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. Hence, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant. Reasoning for above behaviour is the same as given under plant height. The lowest fruit length was recorded under farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ) during both the years of experimentation. Above result is attributable to the same reasoning as given under plant height parameter. During 2010 (at 8 th picking), trend of fruit length data was similar to that found under 8 th picking of year 2009 (Table 4.1). It can be summed up from above account that various treatments did not influence fruit length significantly at 2 nd and 5 th pickings. However, at 8 th picking, VAM inoculated treatments gave significantly higher fruit length (12%) than non-vam inoculated ones and GRD. The above trend might be because of higher nutrient utilization in case of VAM inoculated plants which resulted into enhanced fruit characteristics of okra. Mycorrhizal fungi have the ability to explore a large volume of soil through mycelial growth, thereby enabling plant root system to absorb nutrients and water from soil efficiently. This was consequently reflected as enhanced fruit attributes of okra. Kumar (2010), who worked under similar conditions of soil and climate recorded similar increases as above, which is attributed to above reasoning only. Bahadur and Manohar (2001) working under humid climate and loamy soil, reported that combined application of VAM and 75 per cent of recommended P dose (GRD) gave same fruit parameters (okra fruit length, fruit diameter and average fruit weight), as given by 100 per cent P dose (GRD) only.

83 63 ii. Fruit girth At 2 nd picking, during both the years of experimentation, there were nonsignificant differences in respect of above parameter amongst various treatments (Table 4.2). At 5 th picking (during 2009 and 2010), highest fruit girth was recorded under V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 100% I 40%, all of which were found to be statistically alike. Further, differences amongst various treatments were also observed to be nonsignificant barring farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ), which was found to be significantly inferior to all above treatments. Pooled analysis of data for both the years i.e and 2010 in respect of fruit girth led to same trend as above (Table 4.2). It is obvious from the data presented in Table 4.2 that during 2009, at 8 th picking, the maximum and significant increase in above parameter was recorded under V 12 P 100% I 80% and V 12 P 100% I 40%, both of which exhibited an increase of 14 per cent each over GRD. In case of treatments: V 12 P 100% I 80% and V 12 P 75% I 40%, fruit length was found to be of the same order i.e. 14 per cent, in comparison with GRD. Further, values of above parameter given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments were 8, 8 and 24 per cent higher than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% (Table 4.2). The respective increases in above parameter were to the tune of 14, 17 and 11 per cent in case of treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, respectively over V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, fruit girth given by V 12 P 100% I 80% and V 12 P 75% I 80% did not differ significantly than V 12 P 100% I 40% and V 12 P 75% I 40%. The treatments V 0 P 100% I 80% and V 0 P 100% I 40% and V 0 P 75% I 80% and V 0 P 75% I 40% did not differ significantly and again, gave the same performance in case of above parameter. Hence, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant. The reasoning for above behaviour is the same as given under plant height. Across all the pickings and during both the years, the lowest values of fruit girth were found under farmers practice (V 0 N 25% P 0 K 0 FYM 2.5t I WA ). This result is attributable to same logic as given under plant growth parameter. It is obvious from the data presented in Table 4.2 that during 2010, trend of fruit girth was similar to that under the year 2009.

84 64 Table 4.2 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit girth (cm) during crop growth 2 nd picking 5 th picking 8 th picking Treatment Pooled Pooled Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS NS Treatment detail appears on page 30

85 65 Statistical pooling of data in respect of fruit girth data belonging to two years of investigation led to the same trend as above (Table 4.2). It can be concluded that various treatments did not influence fruit girth significantly at 2 nd and 5 th pickings. However, at 8 th picking, VAM inoculated treatments showed significantly higher fruit girth (11%) than non-vam inoculated ones and GRD. The same reasoning as given under fruit length parameter also holds good here. iii. Average fruit weight At 2 nd picking, 2009, highest value of above parameter was recorded under V 12 P 100% I 80% followed by V 12 P 100% I 40% and V 0 100%NPK FYM 6.4t I AR / GRD, all of which were found to be statistically at par with one another (Table 4.3). However, average fruit weights given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% were significantly higher by 6, 7 and 12 per cent, respectively than their counterpart treatments involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. However, differences in respect of above parameter between V 12 P 100% I 40% and V 0 P 100% I 40% and between V 12 P 75% I 40% and V 0 P 75% I 40% were found to be non-significant. However, at lower level of applied P, significant differences were observed and magnitude of increase was 12 per cent under V 12 P 50% I 40% treatment over V 0 P 50% I 40%. During 2010, (at 2 nd picking), above parameter gave a similar trend as found in case of 2 nd picking of Further, pooled analysis of data belonging to two years gave the same trends as found during 2009 and 2010 (Table 4.3). At 5 th picking, 2009, maximum and significant increase in fruit weight was observed under V 12 P 100% I 80%, which gave respective increases of 6 and 4 per cent over V 0 100%NPK FYM 6.4t I AR / GRD and V 12 P 75% I 80%, respectively (Table 4.3). The treatment V 12 P 100% I 40% gave 5 per cent higher fruit weight than GRD. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% exhibited increases of 4, 8 and 7 per cent in average fruit weight, respectively over V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. A similar trend was found in case of treatments involving irrigation at 40 per cent of AWC at varying levels of P in the presence and absence of VAM. Further, at 8 th

86 66 Table 4.3 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit weight (g) during crop growth Treatment 2 nd picking 5 th picking 8 th picking Pooled Pooled Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

87 67 picking, trend found was similar to that obtained during 5 th picking. Moreover, pooled analysis of data for the two years of study gave similar trends as described above. During 2010 (at 5 th, 8 th picking and pooling of data), same trends as found in case of 5 th picking of 2009 were observed (Table 4.3). Further, during the two years of experimentation (across all above stages), effects due to irrigation regimes were found to be non-significant, irrespective of VAM and P levels. The average fruit weight given by V 12 P 100% I 80% and V 12 P 75% I 80% did not differ significantly than V 12 P 100% I 40% and V 12 P 75% I 40%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were also observed to be non-significant. The same reasoning as given under plant growth parameters holds true here also. It can be deduced that, across all pickings, VAM inoculation involving treatments gave significantly higher average fruit weight (12%) than non-vam inoculated ones and GRD. Higher fruit weight under VAM involving treatments might be because of higher availability of nutrients and water. The improvement in yield attributes could also be partially because of production of growth substances like indole acetic acid and gibberlic acid by VAM, which in turn, might have increased the availability and uptake of nutrients through plant roots. Bahadur and Manohar (2001) also observed higher fruit weight of okra under combined use of VAM and P under a neutral soil rating high in available P status, under semi-arid climatic conditions. iv. Fruit number per kg The data presented hereunder include information evolved on the basis of measurements made at alternate pickings of okra fruits. During 2009, at 2 nd picking, lowest fruit number per kg was recorded under V 12 P 100% I 80%, V 12 P 100% I 40% and V 0 100%NPK FYM 6.4t I AR / GRD, all of which performed statistically alike. The differences in above parameter between V 12 P 100% I 40%, V 12 P 75% I 40% and GRD were also observed to be non-significant. However, V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significantly less i.e. 5, 6 and 11 per cent less fruit number per kg, respectively than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. However, values of above parameter given by V 12 P 100% I 40% and V 12 P 75% I 40% treatments, did not differ significantly than treatments V 0 P 100% I 40% and V 0 P 75% I 40%.

88 68 Table 4.4 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit number kg -1 during crop growth Treatment 2 nd picking 5 th picking 8 th picking Pooled Pooled Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

89 69 But, treatment V 12 P 100% I 40% exhibited an increase of 11 per cent in above parameter over V 0 P 100% I 40% (Table 4.4). During 2010, at 2 nd picking, the same trend as above was observed. Further, statistical pooling of data covering the two years of study gave the same trend as described above (Table 4.4). At 5 th picking, during 2009, lowest fruit number per kg was recorded under V 12 P 100% I 80% followed by V 12 P 100% I 40% and V 12 P 75% I 40%, all of which were observed to be statistically alike. Moreover, above treatments performed statistically at par with GRD. However, V 12 P 75% I 80% gave significantly lower (8%) fruit number per kg than treatments involving same P and irrigation levels without VAM inoculation (V 0 P 75% I 80% ). A similar trend was obtained in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM at varying levels of applied P. During 2010, same trend as found in case of 5 th picking of 2009 was observed. Further, pooled analysis of data for the two years of study gave similar trends as described above (Table 4.4). At 8 th picking 2009, V 12 P 100% I 80% gave 11 per cent lower fruit number per kg as compared to GRD. Likewise, a decrease of 8 per cent in above parameter was found under V 12 P 75% I 80% than GRD. Further, values of above parameter decreased by 10 and 9 per cent under V 12 P 100% I 40% and V 12 P 75% I 40%, respectively in comparison with GRD. Also, significantly lower fruit number was recorded in VAM inoculated plants as compared to non-vam inoculated ones at different P and irrigation levels. During 2010, the same trend as found in case of 8 th picking of 2009 was observed. Further, pooled analysis of data for both the years (2009 & 2010) gave the same trends as described above (Table 4.4). Further, during the two years of experimentation (at above two stages of measurement), differences in fruit number per kg between treatments V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 12 P 50% I 80% and V 12 P 50% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were found to be non-significant. As such, irrespective of VAM and P levels, effects due to irrigation regimes were observed to be non-significant. The same reasoning as given under plant growth parameters holds true here also.

90 70 The lowest fruit number per kg at 2 nd, 5 th and 8 th pickings was recorded under farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ) during both the years of investigation. It is attributable to same reasoning as given under plant growth parameters. The reason for less fruit number per kg in case of VAM involving treatments under varying levels of P is obvious i.e. increase in pod weight, led to a decrease in number of fruits per kg in case of above treatments. Further, mycorrhizal fungi have the ability to explore a larger volume of soil through its mycelial growth, thereby enabling plant root system to absorb nutrients and water from soil efficiently. It led to enhanced fruit characteristics of okra. It can be summarized that, across all pickings, VAM inoculation involving treatments gave showed significantly lowered fruit number per kg (8%) than non-vam inoculated ones and GRD. Overall, in general, it can be deduced from information presented above that yield contributing characters (fruit length, girth, number and weight) at 2 nd and 5 th pickings were marginally influenced by VAM inoculated treatments than non-vam inoculated ones. However, at 8 th picking, mycorrhizal plants gave significantly higher values of above characters. Further, it is notable that in case of VAM involving treatments, moisture and nutrient contents estimated through relevant measurements were much higher than their non-vam counterparts. As such, mycorrhizal plants maintained plant vigour for a longer period Yields The yield data of the experiment are presented in Table 4.5. During 2009, highest fruit yield was recorded under V 12 P 100% I 40% followed by V 12 P 100% I 80% and V 0 100%NPK FYM 6.4t I AR / GRD, all of which were found to be statistically alike. Further, fruit yield given by V 12 P 100% I 80% treatment did not differ significantly than V 0 P 100% I 80%. The treatments V 12 P 75% I 80% and V 12 P 50% I 80% gave significantly higher i.e. 10 and 9 per cent fruit yield, respectively over V 0 P 75% I 80% and V 0 P 50% I 80%. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. Further, it is evident from data presented in Table 4.5 that during 2010, treatment-wise trend with respect to above

91 71 parameter was similar to that found during However, yield levels obtained during 2010 were comparatively lower than 2009 due to poor and delayed germination following continuous rainfall (please refer appendix-2). Irrespective of VAM and irrigation levels, fruit yield increased with each additional increment of P dose. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 11 per cent each over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant respective increases of 7 and 15 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 6 and 13 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively (Table 4.5). Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. It is obvious that the above treatments gave statistically similar performance at each of the two irrigation regimes. The same reasoning as given under plant height parameter also holds good here. Lowest okra fruit yield was recorded under farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ). It is evident from data presented in Table 4.5 that during 2010, treatment-wise trend with respect to above parameter was similar to that found during Further, pooling of data for the two years, in respect of above parameter, gave trends statistically similar to these obtained during individual years as described before (Table 4.5). The yield data presented above clearly suggest that fruit yield given by VAM + 75 per cent P (soil test base) did not differ significantly than GRD and VAM per cent P dose. It suggests an economy of about 25 per cent in soil test based P dose.

92 72 Table 4.5 Effect of integrated application of VAM, phosphorus and irrigation on fruit yield (q ha -1 ) of okra crop Treatment Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) The treatment detail appears on page 30

93 73 The application of VAM enhanced yield attributes of okra (fruit length, fruit girth and average fruit weight), which consequently resulted in higher yield of above crop. Higher yield obtained in case of VAM inoculated plants is attributable to a greater utilization of nutrients particularly P by plants as a result of their efficient mobilisation by VAM fungi. In a study involving an acid Alfisol, wet temperate condition and okra crop, Kumar (2010) reported that 100 per cent soil test based P dose gave statistically the same yield as given by 75 per cent P dose treatment coupled with VAM inoculation. Above report implies a saving in fertilizer P to the tune of about 25 per cent. Suri et al. (2010), working under same conditions as above (Palam Valley) with soybean crop, have also reported a net saving of fertilizer P to the extent of about 25 per cent Agronomic efficiency of P based on response ratio Above parameter was computed to evaluate biological efficiency of phosphorus applied under various treatments. The relevant information is presented in Table 4.6. It is obvious from the data presented in above table that during 2009, there was an impressive increase in P response ratio due to use of mycorrhizal biofertilizer (VAM) in concerned treatments (Table 4.6). The treatment V 0 100%NPK FYM 6.4t I AR / GRD gave relatively a lower response ratio due to higher P dose. Irrespective of VAM and irrigation levels, treatment involving 50 per cent of soil test based recommended P dose gave a higher response ratio. However, in pursuance of the law of diminishing returns, it decreased as the P levels increased, with every additional increment of P. The P response ratio given by V 12 P 50% I 80% and V 12 P 75% I 80% treatments was significantly higher by 20 and 21 per cent, respectively than their counterpart treatments involving same P and irrigation levels without VAM inoculation i.e. V 0 P 50% I 80% and V 0 P 75% I 80% treatments. However, differences between V 0 P 100% I 80% and V 0 P 100% I 80% treatments were found to be non-significant, probably due to lower efficiency of VAM fungi at higher P levels. The data of current study depicted in Fig.(s) 4.21 & 4.22 are also supportive of above statement. A similar trend was obtained under treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM inoculation at varying levels of applied P. Further, data showed a similar trend in case of P response ratio during the next year i.e (Table 4.6).

94 74 Table 4.6 Effect of integrated application of VAM, phosphorus and irrigation on agronomic efficiency of P based on response ratio (kg yield kg -1 P) of okra Treatment V T 0 100%NPK FYM 6.4t 1 I AR (GRD) V T 0 N 25% P 0 K 0 FYM 1.6t I WA 2 (FP) Yield (kg ha -1 ) P applied as P 2 O 5 (kg ha -1 ) P response ratio (kg yield kg -1 P) Yield (kg ha -1 ) P applied as P 2 O 5 (kg ha -1 ) P response ratio (kg yield kg -1 P) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

95 75 Irrespective of VAM and irrigation levels, a decrease in P response ratio was observed with increasing P levels from 50 to 100 per cent of soil test based dose. The values of P response ratio given by treatment V 12 P 50% I 80 were 25 and 63 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 100% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 28 and 61 per cent under V 12 P 50% I 40% treatment over V 12 P 75% I 40% and V 12 P 100% I 40% treatments. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. values of P response ratio given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. The same reasoning as given under plant growth parameters holds true here also. It is notable that during 2010, treatment-wise trend in respect to above parameter was similar to that found during 2009 (Table 4.6). It can be summarized from data presented above that VAM inoculated plants along with P application gave higher P response ratio (7%) as compared to non-vam inoculated ones due to solubilisation/ mobilisation of native/ applied P, thereby, enhancing its availability to plants. The general trend of response ratio data can be explained through the law of diminishing returns (Voisin 1962). However, higher response ratio in case of VAM involving treatments under varying levels of P is obviously the outcome of higher okra productivity. In a study involving tomato under matching conditions, Dhinakaran and Savithri (1997) found an increase of 32 per cent in P use efficiency under VAM inoculation kg P 2 O 5 ha -1 treatment, which is attributable to above reasons.

96 Plant water status i Relative leaf water content (RLWC) The information pertaining above parameter is presented in Table 4.7. The data show that RLWC increased sharply in different treatments at different stages of okra growth. During 2009, at 50 DAS, highest RLWC, was recorded under V 12 P 100% I 80% at morning time (0700 hrs) followed by V 12 P 75% I 80% and V 0 100%NPK FYM 6.4t I AR / GRD, all of which were found to be statistically at par with one another. The treatment V 12 P 100% I 40% and V 12 P 75% I 40% gave the same value of RLWC as given by GRD during early morning hours (Table 4.7). However, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 2, 2 and 1 per cent than their non-vam counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, magnitude of increase in above parameter was to the tune of 12 per cent each in case of treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% than V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Further, a cursory look at data presented in Table 4.7 reveals that in the afternoon (1400 hrs), treatments V 12 P 100% I 80% gave highest RLWC followed V 12 P 75% I 80%. Both the above treatments gave significantly higher (26% each) value of RLWC over GRD. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 1, 2 and 2 per cent, respectively than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. A similar trend of RLWC was found in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM at varying levels of applied P (Table 4.7). Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose, did not differ significantly in respect of above parameter than those involving 75 and 50 per cent of P dose, during the two years of investigation (both during morning and afternoon hours). But, RLWC increased sharply with increasing P levels from 50 to 100 per cent of recommended P dose based soil test. During 2010, at 50 and 75 DAS, treatments-wise trends in RLWC were similar to that observed during the year 2009 (Table 4.7). During the two years of study, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-

97 77 Table 4.7 Effect of integrated application of VAM, phosphorus and irrigation on relative leaf water content (%) during okra crop growth 50 DAS 75 DAS Treatment Morning Afternoon Morning Afternoon Morning Afternoon Morning Afternoon T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

98 78 significant i.e. values of RLWC given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be nonsignificant. The same reasoning as given under plant growth parameters holds true here also. During the two years of investigation, lowest value of RLWC was recorded under farmers practice (V 0 N 25% P 0 K 0 FYM 2.5t I WA ) at different stages of crop growth. It can be concluded from data presented above that, on the whole, integrated application of VAM, P and irrigation maintained a higher relative leaf water content by 27 per cent. The probable reason for high RLWC in treatments involving VAM inoculation as compared to non-vam inoculated ones, at similar levels of P and irrigation regimes, is that the mycorrhizal plants are able to maintain higher tissue water content, which might impart greater drought resistance power to the plants. Farahani et al. (2008) conducted a pot experiment and reported a higher RLWC in coriander under integrated application of VAM and P under drought stress condition. Further, water stressed plants have been found to accumulate organic osmolytes such as sugars and aminoacids (proline) that are known to contribute to host plant tolerance under water deficit conditions (Aziz et al. 2000). The accumulation of proline and total soluble sugars in roots could have provided the roots with an osmotic mechanism to maintain a favourable potential gradient for water entrance into the roots (Irigoyen et al. 1992), thus leading to a lower stress injury to the plants. ii Water use efficiency (WUE) The information on WUE as affected by various treatments imposed in okra crop is presented in Table 4.8. During 2009, highest WUE was recorded under V 12 P 100% I 40% followed by V 12 P 75% I 40%, both of which gave significantly higher WUE i.e. 18 and 14 per cent, respectively than V 0 100%NPK FYM 6.4t I AR / GRD. However, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and GRD happened to be statistically alike vis-à-vis WUE. The treatment V 12 P 75% I 80% and V 12 P 50% I 80%, gave significantly higher WUE by 11 and 9 per

99 79 Table 4.8 Effect of integrated application of VAM, phosphorus and irrigation on water use efficiency (kg ha -1 mm -1 ) of okra crop Treatment Yield (kg ha -1 ) TWU (mm) WUE (kg ha -1 mm -1 ) Yield (kg ha -1 ) TWU (mm) WUE (kg ha -1 mm -1 ) (1) (2) (1 2) (1) (2) (1 2) V T 0 100%NPK FYM 6.4t I AR (GRD) (2) (0) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) (1) (0) T 3 V 0 P 50% I 40% (1) (0) T 4 V 0 P 75% I 40% (1) (0) T 5 V 0 P 100% I 40% (1) (0) T 6 V 12 P 50% I 40% (1) (0) T 7 V 12 P 75% I 40% (1) (0) T 8 V 12 P 100% I 40% (1) (0) T 9 V 0 P 50% I 80% (2) (0) T 10 V 0 P 75% I 80% (2) (0) T 11 V 0 P 100% I 80% (2) (0) T 12 V 12 P 50% I 80% (2) (0) T 13 V 12 P 75% I 80% (2) (0) T 14 V 12 P 100% I 80% (2) (0) CD (P=0.05) *Figures within parentheses show the number of irrigations applied (50 mm each); Effective rainfall (mm): During 2009= 251 mm & during 2010= 352 mm); Total water used= water applied through irrigation (mm) + effective rainfall (mm)

100 80 cent, respectively than their counterparts involving similar P and irrigation levels without VAM inoculation i.e. V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 7 and 6 per cent in above parameter were found under V 12 P 75% I 40% and V 12 P 50% I 40% than their non-vam counterparts involving similar P and irrigation levels i.e treatments V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in WUE was recorded with increasing P levels from 50 to 100 per cent based on soil test. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 40% and V 12 P 75% I 40% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 10 and 11 per cent, respectively over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant increases of 7 and 15 per cent over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Further, magnitude of increase in above parameter was to the order of 6 and 13 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. It is notable that during 2010, treatment-wise trend in respect to above parameter was similar to that found during 2009 (Table 4.8). Irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. WUE given by treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% was significantly higher by 17, 15 and 16 per cent, respectively than V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%. Further, increases in above parameter were to the tune of 17, 18 and 19 per cent under V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40% treatments as compared to V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. During 2010, highest WUE was recorded under V 12 P 100% I 40% followed by V 12 P 100% I 80% and GRD, all of which were found to be statistically alike. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave 11, 17 and 21 per cent higher WUE, respectively than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Further, respective increases of 8, 15 and 22 per cent in above parameter were found under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% than their non-vam counterparts involving similar P and irrigation levels i.e treatments V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%.

101 81 Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. values of WUE given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be nonsignificant. The same reasoning as given under plant growth parameters holds true here also. The lowest WUE was recorded under farmers practice (V 0 N 25% P 0 K 0 FYM 1.6t I WA ). It is attributable to the same logic as given under plant growth parameters. On the basis of information presented above, it can be summarized that VAM involving treatments gave, on an average, 11 per cent higher water use efficiency at varying levels of applied P and irrigation regimes. According to Hardie and Leyton (1981), higher water use efficiency in mycorrhizal plants might be due to ability of roots to absorb soil moisture, thereby maintaining stomata in open condition. Enhanced water conductivity has been attributed to increased area for water uptake facilitated by fungal hyphae in soil. The high dry matter production resulting from use of VAM fungi in crops might partially explain why mycorrhizal plants gave higher WUE than non-mycorrhizal ones (Al-Karaki and Al-Radded 1997). Another reason for higher WUE in case of mycorrhizal plants is the development of more roots as well as requirement of more water to sustain high plant growth rate, which might have influenced a greater water use by mycorrhizal plants (Nagarathna et al. 2007). As per Farahani et al. (2008), the mechanism involved for higher WUE in case of VAM inoculated plants is that mycorrhizal hyphe penetrate soil pores which are inaccessible to root hairs and as such, they absorb water that is not available to non-mycorrhizal plants. Needless to say that VAM inoculation results into the establishment of great fungal hyphal network, which through the processes of solubilisation and mobilisation enhances availability of almost all essential nutrients especially P, which obviously contributes to higher WUE to a great extent. The similar findings as above were reported by Kothari et al. (1990) and Al- Karaki (1998) with maize and wheat grown under warm humid climate and calcareous

102 82 soil. They attributed the responses obtained, following VAM inoculation to same logic as given above Root parameters The root studies, carried out at maximum flowering stage, are based on single replication data only. i. Maximum rooting length The data on maximum rooting length recorded at maximum flowering stage are depicted in Fig. (s) 4.13 and During 2009, maximum and significant increases in above parameter were found in case of V 12 P 100% I 40% and V 12 P 75% I 40%. Each of the above two treatments gave 13 per cent higher maximum rooting length than GRD. Increases in maximum rooting length under V 12 P 100% I 80% and V 12 P 75% I 80% were to the tune of 12 and 8 per cent over GRD. Further, V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significant respective increases of 11, 12 and 10 per cent in above parameter than their counterparts involving same P and irrigation levels in the absence of VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, increases of 15, 20 and 13 per cent in above parameter were recorded under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40%, respectively than V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 75% I 40% (Fig. 4.13). Irrespective of VAM and irrigation levels, maximum rooting length increased with each additional increment of P dose. The values of above parameter given by treatment V 12 P 100% I 80 were 4 and 11 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 14 per cent under V 12 P 100% I 40% treatment over V 12 P 100% I 40%. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels. Irrespective of VAM and P levels, treatments V 12 P 100% I 40% and V 12 P 75% I 40% gave nominal increases of 5 and 1 per cent in above parameter, respectively than V 12 P 100% I 80% and V 12 P 75% I 80%. Further, treatments V 0 P 100% I 80% and V 0 P 75% I 80% gave respective increases of 1 and 2 per cent in above parameter than treatments involving similar VAM and irrigation regimes i.e. V 0 P 100% I 40% and V 0 P 75% I 40% thereby implying that irrigation

103 Maximum rooting length (cm) Maximum rooting length (cm) 83 30,0 24,3 21,4 23,0 24,0 24,1 27,5 27,5 22,2 23,3 24,5 24,5 26,2 27,2 20,0 15,9 10,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting length (cm) of okra during ,0 20,0 23,1 19,4 21,2 22,2 22,4 25,5 25,7 20,2 21,6 22,6 22,4 24,7 25,2 13,9 10,0 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting length (c m) of okra during 2010 Treatment detail appears on page 30

104 84 V 0 P 100% I 80% Vs V 12 P 75% I 80% V 0 P 75% I 80% Vs V 12 P 75% I 80% V 12 P 75% I 40% Vs V 0 P 100% I 40% V 12 P 100% I 40% Vs V 0 100%NPK FYM 10t I AR / GRD V 12 P 100% I 80% Vs V 0 100%NPK FYM 10t I AR / GRD V 12 P 75% I 40% Vs V 0 P 100% I 40% Plate 4.1. Response of okra roots to integrated application of VAM, P and irrigation during 2009

105 85 regimes did not exhibit much influence on above parameter obviously due to equal moisture availability at both the irrigation regimes. During 2010, maximum rooting length data obtained under various treatments followed the same trend as that observed in the previous year (Fig. 4.14). On the basis of information presented above, it can be summarized that VAM inoculation enhanced okra maximum rooting length, on an average, by 10 per cent at varying P and irrigation levels. Song (2005) concluded that soil inoculation with VAM increased maximum rooting length: Above trend is attributable to increased number of higher order laterals in VAM inoculated treatments than non-vam inoculated ones. In pot experiments with maize and tomato involving low available P soils, Kothari et al. (1990) and Edathil et al. (1996) observed 17 and 53 per cent respective increases in maximum rooting length under combined use of VAM and P than absolute control. ii. Root Volume During 2009, V 12 P 100% I 40% and V 12 P 75% I 40% gave 8 and 16 per cent higher root volume than V 0 100%NPK FYM 6.4t I AR / GRD. Likewise, increases in root volume under V 12 P 100% I 80% and V 12 P 75% I 80% were higher by 6 and 3 per cent, respectively in comparison with GRD (Fig. 4.15). Further, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 3, 5 and 7 per cent each in above parameter than their non-vam counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, increases of 6 and 10 per cent in root volume were found under V 12 P 75% I 40% and V 12 P 50% I 40%, respectively than V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in root volume was observed with increasing P levels from 50 to 100 per cent based on soil test. The values of above parameter given by treatment V 12 P 100% I 80 were 1 and 7 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 4 and 12 per cent in case of V 12 P 100% I 40% treatment over V 12 P 75% I 40% and V 12 P 50% I 40%. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels.

106 Root volume (ml) Root volume (ml) ,5 13,5 13,6 12,7 12,7 12,8 11,6 10, ,9 13,4 12,8 13,6 13,8 5 0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of okra during ,0 18,7 17,3 18,0 18,5 18,7 19,8 20,2 17,1 17,7 18,4 18,3 19,2 19,9 14,0 11,4 7,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of okra during 2010 Treatment detail appears on page 30

107 87 Irrespective of VAM and P levels, treatments involving irrigation at 80 per cent of AWC at varying levels of P in the presence and absence of VAM inoculation gave almost similar values of root volume than treatments involving irrigation at 40 per cent of AWC. It can be deduced that various treatments behaved similarly at both the irrigation regimes. The probable reason for above results is attributable to almost equal availability of moisture in soil under the two irrigation regimes, as all experimental plots received good and equal amount of rainfall (1274 mm during 2009 & 2076 mm during 2010) during the cropping seasons. During 2010, root volume data obtained under various treatments gave the same trend as observed during the previous year (Fig. 4.16). Based on information presented above, it can be summarized that VAM inoculation enhanced root volume, on an average, by 10 per cent at varying P and irrigation levels. The higher root volume values are attributable to extension of crop root system into soil profile by way of development of higher order laterals through ramification of fungal hyphae associated with it. Present results are in agreement with the findings of Singh (2011), who found higher root volume of broccoli resulting from vermicomposting (5 t ha -1 ) and irrigation management practices under an acid Alfisol of temperate climate. iii. Root dry weight During 2009, an increase of 4 per cent in above parameter was observed under each of the two treatments i.e. V 12 P 100% I 40% and V 12 P 75% I 40% than V 0 100%NPK FYM 6.4t I AR / GRD. Similarly, increase in root dry weight with V 12 P 100% I 80% and V 12 P 75% I 80% was 3 and 2 per cent higher over GRD (Fig. 4.17). Further, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave nominal increases of 1, 3 and 2 per cent in above parameter than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 4, 5 and 2 per cent in above parameter were found under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% than treatments involving same levels of applied P and

108 Root dry weight (g) Root dry weight (g) 88 6,00 4,50 4,37 4,31 4,34 4,38 4,38 4,54 4,54 4,29 4,36 4,43 4,36 4,47 4,49 3,00 2,96 1,50 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of okra during ,50 5,00 6,42 5,02 5,52 5,86 6,02 6,45 6,62 4,98 5,46 5,82 6,00 6,44 6,60 3,19 2,50 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of okra during 2010 Treatment detail appears on page 30

109 89 irrigation regimes in the absence of VAM inoculation i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in root dry weight was observed with increasing P levels from 50 to 100 per cent applied on soil test basis. The values of above parameter given by treatment V 12 P 100% I 80 were 1 and 3 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 2 and 3 per cent in case of V 12 P 100% I 40% treatment over V 12 P 75% I 40% and V 12 P 50% I 40%. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels. Irrespective of VAM and P levels, treatments involving irrigation at 80 per cent of AWC at varying levels of P in the presence and absence of VAM inoculation gave almost similar values of above parameter than treatments involving irrigation at 40 per cent of AWC. It is attributable to same reasoning as given under root volume. During 2010, root dry weight data gave the same treatment-wise pattern as observed in the year preceding it i.e (Fig. 4.18). On the basis of information presented above, it can be summarized that VAM inoculation enhanced pea root dry weights, on an average, by 3 per cent at varying P and irrigation levels. The same reasoning as given under maximum rooting length and root volume holds true here also due to obvious reasons. The present results are in conformity with findings of Rabie and Humiany (2004), who observed increased root dry weights in cowpea under matching soil and climatic conditions due to application of P coupled with VAM. iv. Root weight density Above parameter is a function of root dry weight and actual root volume i.e. the soil volume from which the roots were collected (1.16 m 3 ) and measured. It is obvious that the trend observed herein is the same as in case of root dry weight (Fig. 4.17). During 2009, V 12 P 100% I 40% and V 12 P 75% I 40% gave respective increases of 4 per cent each in root weight density than V 0 100%NPK FYM 6.4t I AR / GRD. The magnitude of

110 Root weight density (g m -3 ) Root weight density (g m -3 ) 90 7,50 5,00 5,75 4,50 4,95 5,25 5,39 5,78 5,93 4,46 4,89 5,22 5,38 5,77 5,91 2,50 2,86 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of okra during ,50 5,00 5,75 4,50 4,95 5,25 5,39 5,78 5,93 4,46 4,89 5,22 5,38 5,77 5,91 2,50 2,86 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of okra during 2010 Treatment detail appears on page 30

111 91 increase in above parameter under V 12 P 100% I 80% and V 12 P 75% I 80% was to the tune of 3 and 2 per cent than GRD (Fig. 4.19). Irrespective of P and irrigation levels, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave marginal increases in root weight density i.e. 1, 3 and 2 per cent, respectively in comparison with V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, an increase of 4, 4 and 2 per cent in above parameter was observed under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% than treatments involving same P and irrigation levels without VAM inoculation i.e. V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in root weight density was observed with increasing P levels from 50 to 100 per cent applied on soil test basis. However, treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave almost similar values of above parameter. But, magnitude of increase in above parameter was to the tune of 3 per cent under V 12 P 100% I 80 in comparison with V 12 P 50% I 80% treatment. Likewise, nominal increases of 2 and 3 per cent were recorded in case of V 12 P 100% I 40% treatment over V 12 P 75% I 40% and V 12 P 50% I 40%. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels. Irrespective of VAM and P levels, treatments involving irrigation at 80 per cent of AWC at varying levels of P in the presence and absence of VAM inoculation, gave almost similar values of above parameter than treatments involving irrigation at 40 per cent of AWC. It is attributable to the same reasoning as given under root volume. During 2010, data on above parameter showed the same trend as observed during 2009 (Fig. 4.20). It can be summed up that VAM inoculation enhanced okra root weight density by 1-4 per cent at varying P and irrigation levels. Above trends are attributable to the same logic as given under above root parameters. Present results are in agreement with the findings of Kothari et al. (1990), who conducted a pot experiment with maize involving low available P soil and observed 35 per cent increase in root weight density under combined use of VAM and P than absolute control.

112 92 v. Root colonization with VAM The data pertaining above parameter are depicted in Fig. (s) 4.21 and During 2009, VAM inoculation improved root colonization from 6-27 per cent, whereas, during 2010, its magnitude ranged from 7-31 per cent. Further, it is notable that the percentage of root colonization was maximum under lowest level of applied P and it decreased with increasing levels of P. During 2009, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave increases of 2, 1.5 and 2 folds in above parameter, respectively than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 1.8, 1.8 and 3.4 folds in above parameter were found under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, respectively than treatments V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of irrigation regimes, a decrease in root colonization with VAM were observed with increasing P levels (50 to 100% based on soil test) coupled with VAM inoculation. The values of VAM root colonization given by treatment V 12 P 50% I 80 were 8 and 13 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 100% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 8 per cent each under V 12 P 50% I 40% treatment over V 12 P 75% I 40% and V 12 P 100% I 40% treatments. During the two years of study, irrespective of VAM and P levels, treatments involving irrigation either at 80 or 40 per cent of AWC at varying levels of P with and without VAM inoculation gave almost similar values of above parameter. As such, effects due to irrigation regimes were observed to be non-significant. The same reasoning as given under plant growth parameters holds good here also. It can be concluded that VAM involving treatments enhanced the extent of root colonization with VAM substantially ( folds) than non-vam inoculated ones. Overall, it is inferred that integrated application of VAM, P and irrigation improved various root parameters measured at maximum flowering stage of okra immensely. The probable reason for decreased root colonization with VAM at higher P level is that under P deficient conditions, plant roots released large amount of sugars and amino acids which stimulated colonization (Somani and Kanthaliya 2004).

113 Root colonization with VAM (% ) Root colonization with VAM (% ) T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation colonization with VAM (% ) in okra during 2009 on root T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root colonization with VAM (%) in okra during 2010 Treatment detail appears on page 30

114 94 Fungal hyphae Plate 4.2. Root colonization with VAM (%) in okra under integrated application of VAM, P and irrigation during 2009

115 95 Further, it is obvious that under situation of say 100 or 75 per cent of recommended P supply, above secretions would be to a lesser extent thereby, reducing magnitude of VAM colonization. Another reason for lesser root colonization at higher levels of applied P is that higher P levels decreased substantially the activities of acid phosphatase enzyme. Under conditions of P deficiency in soil, secretion of acid phosphatase enzyme from roots takes place (Fox and Comford 1990). In a study involving an acid Alfisol, wet temperate condtion and okra crop, Kumar (2010) observed lower percentage of root colonization with VAM at higher level of applied P (100% of soil test based recommended dose ) than lower ones i.e. 75 and 50 per cent of applied P Quality parameters The information on the impact of integrated application of VAM, phosphorus and irrigation on above parameters is presented in Table 4.9. Above information covers Ca, Fe and crude protein status of okra fruits. i. Calcium The various treatments influenced Ca status of okra fruits significantly. During 2009, a significant increase of 10 per cent in each of the above parameters was observed under each of the 2 treatments i.e. V 12 P 100% I 80% and V 12 P 100% I 40% than V 0 100%NPK FYM 6.4t I AR / GRD. The treatments V 12 P 75% I 80% and V 12 P 75% I 40% also gave significantly higher i.e. 8 per cent in each case, than GRD (Table 4.9). Irrespective of P and irrigation regimes, treatments involving VAM inoculation gave significantly higher Ca content in okra fruits. In case of treatments: V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, Ca content was found to be of same tune i.e. 14 per cent, than their non-vam counterparts involving same levels of P and irrigation regimes i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 14 per cent in above parameter were observed under each of the 3 treatments i.e. V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40% as compared to V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose did not differ significantly in respect of Ca content than those involving 75 and 50 per cent of recommended P dose during the two years of

116 96 investigation. But, values of above parameter increased nominally with increasing level of P. Irrespective of VAM and P levels, effect due to irrigation regimes was found to be non-significant i.e. Ca content given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also found to be nonsignificant. During 2010, treatment-wise trend of Ca content was similar to that obtained during The relevant pooled analysis (Table 4.9) gave the same trend as observed during each of the 2 years of experimentation. It can be concluded that integrated application of VAM, phosphorus and irrigation enhanced Ca content, on an average, by 12 per cent in pea seeds than GRD and treatments not involving VAM culture. This is a case of nutrient mobilisation than solubilisation as Ca is most mobile nutrient; it leaches substantially in acid soils especially in high rainfall regions. As such, VAM fungi help to mobilise Ca from deeper layers through their hyphae and make it available to plants. Therefore, VAM culture involving treatments showed a higher Ca concentration in okra fruits. Present results are in conformity with findings of Goicoechea et al. (1997), who found higher Ca concentration in VAM inoculated alfalfa plants grown under clay loam soil and temperate condition. ii. Iron It is notable that none of the treatments influenced plant Fe content significantly except V 0 N 25% P 0 K 0 FYM 1.6t I WA / Farmers practice during both the years of study (Table 4.9). Farmers practice was the lowest performer vis-à-vis plant Fe content.

117 97 Table 4.9 Effect of integrated application of VAM, phosphorus and irrigation on okra fruit quality Treatment Ca (%) Fe (mg kg -1 ) Crude protein (%) Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS Treatment detail appears on page 30

118 98 Kucey and Janzen (1987) working under similar situations of soil and climate reported that crop (fieldbean) roots alone are effective enough to absorb required amount of Fe from soil and therefore, there was a low response to VAM inoculation. However, Kumar (2010) estimated higher Fe concentration in okra fruit under combined application of VAM and soil test based recommended P in acid soils and temperate condition. iii. Crude protein The crude protein content was influenced favourably by various treatments. During 2009, an increase of 2 per cent in above parameter was found under each of the two treatments i.e. V 12 P 100% I 80% and V 12 P 75% I 80% in comparison with V 0 100%NPK FYM 6.4t I AR / GRD. A similar increase of 2 per cent than GRD in each of the 2 treatments i.e. V 12 P 100% I 40% and V 12 P 75% I 40% was also observed (Table 4.9). Further, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 2, 3 and 4 per cent in protein content than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, increases of 2, 3 and 3 per cent in above parameter were found under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40% than treatments involving same levels of P and irrigation regimes in the absence of VAM biofertilizer i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose, did not differ significantly in respect of crude protein content than those involving 75 and 50 per cent of P dose during the two years of investigation. But, values of above parameter increased nominally with increasing level of P. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. crude protein content given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. During 2010, the same trend as above was noticed (Table 4.9).

119 99 It can be deduced from above that integrated application of VAM, phosphorus and irrigation enhanced crude protein content nominally (4%) in okra fruits than GRD and treatments not involving VAM culture. However, effects due to irrigation regimes were observed to be non-significant. Overall, it can be inferred that VAM inoculation at varying levels of P and irrigation regimes improved quality (Ca and protein) of okra fruits substantially. But, above input did not affect its iron content. The better quality of okra fruits following VAM inoculation in the presence of phosphorus is attributable to the fact that mycorrhizal fungi facilitated additional nutrient absorption from deeper layers of soil. The acid Alfisols are highly susceptible to leaching of N and Ca because of high rainfall. As such, VAM fungi are capable of mobilising nutrients from lower layers. As crude protein content depends upon N concentration in plants, application of P and VAM improved plant N concentration resulting in enhanced protein content of okra fruits. Present results are in conformity with findings of Prasad and Prasad (1998), who have reported an increase of 11 per cent in above parameter in garden pea seeds with 90 kg P 2 O 5 ha -1 under warn and humid conditions Nutrient uptake The data on nutrient uptake by okra are given in Table i. N uptake During 2009, an increase of 5 per cent in each of the 2 treatments i.e. V 12 P 100% I 80% and V 12 P 100% I 40% was observed than V 0 100%NPK FYM 6.4t I AR / GRD (Table 4.10). The N uptake in case of V 12 P 100% I 80% and V 0 P 100% I 80% did not differ significantly. The treatments V 12 P 75% I 80% and V 12 P 50% I 80% gave significant respective increase of 6 and 5 per cent in above parameter than V 0 P 75% I 80% and V 0 P 50% I 80%. A similar trend in above parameter was obtained under treatments involving irrigation at 40 per cent of AWC at varying levels of P in the presence and absence of VAM inoculation. Irrespective of VAM and irrigation levels, N uptake increased with increasing P levels. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of

120 100 Table 4.10 Effect of integrated application of VAM, phosphorus and irrigation on total N, P and K (kg ha -1 ) uptake by okra crop Treatment N P K Pooled Pooled Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

121 101 mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 6 and 13 per cent, respectively over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant respective increases of 5and 15 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 5 and 16 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. values of N uptake given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. During 2010, highest N uptake was recorded under both V 12 P 100% I 80% and V 12 P 100% I 40%, each one followed by GRD. All above treatments were found to be statistically similar in respect of above parameter. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 5, 10 and 6 per cent in above parameter as compared to V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, magnitude of increase in N uptake was to the tune of 6 and 8 per cent in case of V 12 P 75% I 40% and V 12 P 50% I 40% treatments over V 0 P 75% I 40% and V 0 P 50% I 40% treatments. Pooled analysis of data belonging to the two years of study gave the same trend in respect of N uptake as observed during the two individual years i.e and 2010 (Table 4.10). It can be concluded from information presented above that integrated application of VAM, P and irrigation enhanced N uptake, on an average, by 8 per cent as compared to GRD and non-application of VAM. The trend of improved nutrient upotake in okra plants following VAM application is obvious as mycorrhizal fungi possess the ability to mobilise various nutrients (N, K, Ca, Mg, Zn, Mn, Cu, Na, Fe and B) from soil because of their ramifying hyphae associated with plant root system (Goicoechea et al. 1997; Clark and Zeto 2000). Kucey

122 102 and Janzen (1987) also reported that VAM inoculation increased the uptake of P, Zn, Cu and Fe in field beans. Based on their studies, they further stated that phosphatase enzyme produced by VAM fungi play an important role in converting insoluble P into soluble one, which could be utilized by plants. Our results are in conformity with those of Kumar (2010) and Suri et al. (2006), who worked under similar conditions of soil and climate on wheat. ii. P uptake During 2009, uptake of P under V 12 P 100% I 80% and V 12 P 75% I 80% was significantly higher by 15 per cent in each case than V 0 100%NPK FYM 6.4t I AR / GRD. Likewise, V 12 P 100% I 40% and V 12 P 75% I 40% gave significant increases of 15 and 10 per cent in above parameter in comparison with GRD (Table 4.10). The increase in uptake of P was significantly higher by 15, 28 and 24 per cent in case of V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively in comparison with their non-vam counterparts involving same levels of P and irrigation regimes as above i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Irrespective of VAM and irrigation levels, P uptake increased with increasing P levels. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 10 and 15 per cent, respectively over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant respective increases of 11 and 18 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 25 per cent under V 0 P 100% I 40% over V 0 P 50% I 80% treatment. During the two year of study, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. P uptake given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant.

123 103 During 2010, a significant increase (12%) in P uptake was found under V 12 P 100% I 80% than GRD. However, differences between V 12 P 75% I 80% and GRD in respect of above parameter were found to be non-significant. Further, P uptake under V 12 P 100% I 40%, V 12 P 75% I 40% and GRD treatments did not differ significantly (Table 4.10). The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 19, 29 and 13 per cent in above parameter than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Further, increases in P uptake were significantly higher i.e. 13, 20 and 21 per cent under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40%, respectively than their non-vam counterpart treatments involving same levels of P and irrigation regimes i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Statistical pooling of data in respect of above parameter for the two years of investigation gave the same trend as found during 2009 (Table 4.10). On the basis of information presented above, it can be concluded that treatments involving VAM inoculation enhanced P uptake, on an average, by 24 per cent than GRD and non-vam inoculated ones. The same logic as given under N uptake also holds good here. In addition, it is worth pointing out that in case of P, organic acids and enzymes released by plant roots and mycorrhizal fungi play a very special role by way of solubulising insoluble phosphorus and making it available for use by crop plants. iii. K uptake During 2009, a significant increase of 4 per cent in respect of above parameter under each of the 2 treatments i.e. V 12 P 100% I 80% and V 12 P 100% I 40% was observed over V 0 100%NPK FYM 6.4t I AR / GRD. Potassium uptake in case of V 12 P 75% I 80% and GRD did not vary significantly (Table 4.10). Results in respect of above parameter obtained under V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments. However, increase in K uptake was significantly higher by 4 per cent in each case, under treatments V 12 P 100% I 40% and V 12 P 75% I 40% in comparison with treatments involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 40% & V 0 P 75% I 40%.

124 104 During 2010, K uptake in case of V 12 P 100% I 80%, V 12 P 75% I 80%, V 12 P 100% I 40%, V 12 P 75% I 40% and GRD did not vary significantly. Further, differences in above parameter between V 12 P 100% I 80% and V 0 P 100% I 80% and V 12 P 100% I 40% and V 0 P 100% I 40% were also found to be non-significant. However, a significant increase of 6 per cent in respect of above parameter under each of the 2 treatments i.e. V 12 P 75% I 80% and V 12 P 75% I 40% was observed as compared to their counterpart treatments involving same P and irrigation levels without VAM inoculation i.e. V 0 P 75% I 80% and V 0 P 75% I 40%. Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose did not differ significantly in respect of above parameter than those involving 75 and 50 per cent of P dose during the two years of investigation (at both stages). But, K uptake increased nominally with additional increment of P application. During the two year of study, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. K uptake given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. Pooled analysis of data for the two years of study, gave the same trend as observed during 2009 in respect of above parameter (Table 4.10). It can be concluded that treatments involving VAM inoculation enhanced K uptake, on an average, by 5 per cent than GRD and non-vam inoculated ones. Same reasoning as given under N and P uptake also holds good here. iv B uptake The boron (B) uptake as affected by various treatments is presented in Table During 2009, V 12 P 100% I 80% gave maximum (7%) and significant increase in B uptake than V 0 100%NPK FYM 6.4t I AR / GRD. The treatment V 12 P 75% I 80% increased B uptake by 6 per cent than GRD. Further, V 12 P 100% I 40% gave 10 per cent higher B uptake as compared to GRD. However, differences between V 12 P 75% I 40% and GRD were found to be non-

125 105 significant (Table 4.11). The differences in B uptake between V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80% and between V 12 P 50% I 80% and V 0 P 50% I 80% were also observed to be non-significant. A similar trend in above parameter was obtained under treatments involving irrigation at 40 per cent of AWC at varying levels of P in the presence and absence of VAM inoculation. Irrespective of VAM and irrigation levels, B uptake increased with each additional increment of P dose. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 8 and 24 per cent over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant respective increases of 4 and 10 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 6 and 23 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. B uptake given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be nonsignificant. During 2010, treatment-wise trend with respect to above parameter was similar to that found during On the basis of information presented above, it can be concluded that treatments involving VAM inoculation enhanced B uptake, on an average, by 8 per cent than non- VAM inoculated ones. v. Mo uptake Various treatments produced an appreciable effect on Mo uptake by okra during the two years of experimentation (Table 4.11). During 2009, treatments V 12 P 100% I 40% and V 12 P 75% I 40% gave 37 and 30 per cent higher Mo uptake, respectively over V 0 100%NPK FYM 6.4t I AR / GRD. Further, significant increases of 30 and 23 per cent were found under V 12 P 100% I 80% and V 12 P 75% I 80%, respectively than GRD (Table 4.11). The treatments

126 106 Table 4.11 Effect of integrated application of VAM, phosphorus and irrigation on total B and Mo uptake (g ha -1 ) by okra crop Treatment B Mo Pooled T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS Treatment detail appears on page 30

127 107 V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave significant increases of 34, 38 and 33 per cent in above parameter than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%, respectively. Further, Mo uptake was significantly higher by 54, 63 and 59 per cent in case of V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40%, respectively than treatments V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, Mo uptake increased with each additional increment of P dose. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through the use of mycorrhizal fungi. During the two years of study, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. Mo uptake given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. During 2010, it is notable that the trend of Mo uptake was similar to that obtained during It can be inferred that treatments involving VAM inoculation enhanced Mo uptake, on an average, by 43 per cent than non-vam inoculated ones. Overall, it can be summarized from the data presented above that VAM inoculation along with application of P and irrigation gave higher uptake of nutrients as compared to treatments involving no VAM inoculation. The same reasoning as given under N and P uptake also holds good here. 4.2 Effect of integrated application of VAM, phosphorus and irrigation on soil chemical properties after okra harvest i. Soil reaction (ph) The data presented in Table 4.12 revealed that none of the treatments influenced soil ph significantly during either of the two years i.e and 2010.

128 108 Table 4.12 Effect of integrated application of VAM, phosphorus and irrigation on soil ph and organic carbon status (g kg -1 ) after okra harvest Treatment ph Organic carbon T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS Treatment detail appears on page 30

129 109 As it was only a two years experiment and not a long-term one, above parameter was not likely to change significantly due to obvious reason i.e. high buffering capacity of the soil (due to abundant presence of various salts), which implies a high resistance to change in ph (Brady 2002). Fertilizer P does not affect soil ph. Further, as the balanced amounts of N and K on soil test basis were applied, there was a low probability of a change in ph in short term. ii. Organic carbon Unlike, most other parameters, GRD was the top performer by way of status of soil carbon after harvest of each crop as well as after the completion of two-year experiment. Organic carbon status of soil after pea harvest during 2009 and 2010 is given in Table During 2009, highest increase in soil organic carbon was recorded under V 0 100%NPK FYM 6.4t I AR / GRD which was found superior to all other treatments. The GRD exhibited a non-significant increase of 4 per cent each over V 12 P 75% I 80% and V 12 P 100% I 80% treatments. Similarly, GRD gave an increase by 4 per cent in respect of above parameter over each of V 12 P 75% I 40% and V 12 P 100% I 40%. However, differences in above parameter between V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80%, between V 12 P 100% I 40% and V 0 P 100% I 40% and between V 12 P 75% I 40% and V 0 P 75% I 40% were found to be non-significant. During the two years of experimentation, differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. Further, treatments involving 100 and 75 per cent of soil test based recommended P dose combined with VAM inoculation at either of two irrigation regimes i.e. 40 and 80 per cent of AWC (V 12 P 75% I 80% & V 12 P 100% I 80% ; V 12 P 75% I 40% & V 12 P 100% I 40% ) gave statistically similar status of organic carbon. It suggests an economy of about 25 per cent in soil test based fertilizer P dose. During 2010, treatment-wise trend of organic carbon was found similar to that of previous year (Table 4.12).

130 110 Actually, in all field plots except the GRD, only a nominal amount of FYM (1.6 t ha -1 on dry weight basis) was applied with the aim of preparing them for biofertilizer study. On the other hand, in case of GRD, 6.4 t FYM ha -1 on dry weight basis was appleied. Above facts are responsible for the differential amount of organic carbon values found under VAM involving treatments and vice versa. This was done consciously to ensure a fair response to VAM inoculation in the experiment, apprehending the masking of the likely response due to generalized dose of FYM recommendded. Otherwise, there are many reports in literature which suggest a substantial increase in above parameter following continuous and long term application of VAM culture. Further, there are indications of organic matter build up in VAM involving treatments which might improve a lot in the long-term. However, some workers (Jaipaul et al. 2010) while working with capsicum under temperate condition, have reported an increase in soil organic carbon content under combined application of FYM, PSB and 100 per cent P dose (GRD). iii. Available N, P and K status The data on available N, P and K status after okra harvest are given in Table During 2009, in case of N, V 0 100%NPK FYM 6.4t I AR / GRD gave significantly less buildup of available N in soil than other treatments barring farmers practice. However, differences amongst various treatments were found to be non-significant. A similar trend was observed during 2010 (Table 4.13). It is notable that N is the most mobile nutrient element and hence apart from its uptake by crop, it may get lost through processes like leaching, volatilization, etc. (Brady 2002; Havlin et al. 2007). In the present study, leaching phenomenon seems to be the most relevant because of location of experimental site in the high rainfall region. In case of P, during 2009, highest status was recorded under V 12 P 100% I 80%, V 12 P 100% I 40% and V 12 P 75% I 40%, all of which were found to be statistically at par with GRD (Table 4.13). Moreover, differences in above parameter between V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80% and between V 12 P 100% I 40% and V 0 P 100% I 40% were also found to be non-significant. However, treatments V 12 P 75% I 40% and V 12 P 75% I 40% gave significant respective increases of 19 and 15 per cent in respect of

131 111 Table 4.13 Effect of integrated application of VAM, phosphorus and irrigation on available N, P and K status (kg ha -1 ) of soil after okra harvest Treatment N P K T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 30

132 112 above parameter than their non-vam counterparts involving same P and irrigation levels i.e. treatments V 0 P 75% I 40% and V 0 P 75% I 40%. During 2010, available P in soil was recorded to be higher under V 12 P 100% I 40% treatment followed by V 12 P 75% I 40% and V 12 P 100% I 80%, all of which were found to be statistically alike. Further, differences amongst various treatments were also found to be non-significant (Table 4.13). During the 2 years of experimentation, differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. Further, treatments involving 100 and 75 per cent of soil test based recommended P dose combined with VAM inoculation at either of two irrigation regimes i.e. 40 and 80 per cent of AWC (V 12 P 75% I 80% & V 12 P 100% I 80% ; V 12 P 75% I 40% & V 12 P 100% I 40% ) gave statistically similar P status after okra harvest. It suggests an economy of about 25 per cent in soil test based fertilizer P dose. The experimental soil being acidic (1:1 type) with a high level of soluble and exchangeable Al and Fe ions had a high P-fixing power (Sharma et al. 1980). This might be the major reason for low and non-significant recovery of available P in soil after pea harvest. Further, VAM inoculation helped to mobilise and solubilise phosphates in soil by releasing organic acids and phosphatase enzyme which increased availability of P in soil. The results of current study are similar to the findings of Suri et al. (2006), who carried out relevant experiments on exactly matching soil and climatic conditions. In case of K (during 2009), FP and GRD gave significantly lower values than all other treatments. However, differences amongst various treatments (T 3 -T 14 ) were observed to be non-significant. Data in respect of above parameter gave the same trend as observed during 2009 (Table 4.13). The reason for non-significant K recovery in the soil might be that, almost similar amount of K got applied and became available for plant use in all the treatments in the experiment. However, Kumar (2010) while working under matching soil and climatic conditions, has reported increased available K status under combined application of

133 113 VAM and soil test based recommended NPK, who attributed the same to the ability of VAM to enhance availability of various nutrients in the soil. iv. Exchangeable Ca and Mg The information on exchangeable Ca and Mg is given in Table During 2009, highest Ca content was observed under V 0 100%NPK FYM 6.4t I AR / GRD followed by V 12 P 100% I 80% and V 0 P 100% I 80%, all of which were found to be statistically similar. Further, differences amongst various treatments were also found to be non-significant. Similar results were obtained during 2010 (Table 4.14). During 2009, highest Mg status was observed under GRD followed by V 12 P 100% I 80% and V 0 P 100% I 80%, all of which were found to be statistically alike. Further, differences amongst various treatments were also found to be non-significant. Similar results were obtained during 2010 (Table 4.14). It is summarized that none of the treatments influenced soil Ca and Mg status significantly after okra harvest during the two years of study. The reason for non-significant Ca and Mg status after okra harvest is attributable to a high amount of leaching resulting from high rainfall received during both the experimental seasons. v. Available micronutrients The data with respect to available Fe, Zn, Cu Mn, B and Mo status after okra harvest are presented in Table (s) 4.15 and The data revealed that there was a nonsignificant effect of integrated application of VAM, P and irrigation levels on available micronutrient status during the two years of study. It can be inferred from data presented above that soil properties were not affected significantly by integrated application of VAM, P and irrigation. There are reports in literature that various nutrient elements may influence availability of one another especially under their varying levels ranging from low to high (Das 2011). However, the present experiment involved balanced fertilization involving FYM, fertilizer N, P and K and VAM biofertilizer. Therefore, the possibilities of nutrient interactions affecting results are ruled out (Das 2011).

134 114 Table 4.14 Effect of integrated application of VAM, phosphorus and irrigation on exchangeable Ca and Mg status (c mol (p+) kg -1 ) of soil after okra harvest Ca Mg Treatment T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS NS NS Treatment detail appears on page 30

135 115 Table 4.15 Effect of integrated application of VAM, phosphorus and irrigation on soil available Fe, Zn, Cu and Mn status (mg kg -1 ) after okra harvest Treatment Fe Zn Cu Mn T 1 V 0 100%NPK FYM 6.4t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS NS NS NS NS NS NS Treatment detail appears on page 30

136 116 Table 4.16 Effect of integrated application of VAM, phosphorus and irrigation on available B and Mo status (mg kg -1 ) of soil after okra harvest Treatment T 1 V 0 100%NPK FYM 6.4t I AR (GRD) B Mo Pooled T 2 V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS NS NS NS Treatment detail appears on page 30

137 117 The major reason for lesser differences amongst various treatments in respect of above micronutrients is that their initial status in experimental soil was high Moreover, above nutrients were not applied externally. Boron is an anion which gets leached out in acid soils. As such, VAM fungi have potential to mobilise it from deeper soil layers. Soils of wet temperate zone are inherently poor in boron (B). Actually, these soils are derived from granite rocks which are poor in B bearing tourmaline mineral, which probably is the reason for their low B supplying power. The findings of a field experiment conducted by Suri et al. (2011) in wheat, involving a P deficient acid Alfisol under wet temperate condition, revealed that the use of VAM culture alone or in combination with increasing P levels from 50 to 75 per cent of recommended P dose, resulted in a reduction in DTPA extratable micronutrient (Fe, Zn, Cu and Mn) contents over absolute control. 4.3 Economic analysis of experiment under okra The data with respect to economic analysis of experiment under okra during 2009 is presented in Table The different treatments influenced the profitability of okra significantly. The data revealed that treatments V 12 P 100% I 40% and V 12 P 100% I 80% gave significantly higher i.e. 12 and 11 per cent net returns, respectively than V 0 100%NPK FYM 6.4t I AR / GRD. Likewise, significant respective increases of 9 and 7 per cent were found in above parameter in case of V 12 P 75% I 80% and V 12 P 75% I 40% over GRD. The treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave significant increases to the tune of 6 and 13 per cent in net returns than their non-vam counterparts involving same levels of P and irrigation regimes i.e. V 0 P 100% I 80% and V 0 P 75% I 80%. Further, the increase in net returns was significantly higher by 10 per cent under V 12 P 75% I 40% in comparison with treatment involving same P and irrigation regimes without VAM inoculation i.e. V 0 P 75% I 40% (Table 4.17). In case of benefit cost (B:C) ratios, treatments V 12 P 100% I 40% and V 12 P 100% I 80% gave significantly higher i.e. 43 and 42 per cent, respectively benefit cost (B:C) ratio than GRD. Further, respective increases in above parameter were 42 and 39 per cent under V 12 P 75% I 80% and V 12 P 75% I 40% over GRD. The treatments V 12 P 75% I 80% gave a significant

138 118 Table 4.17 Economic analysis of experiment under okra T 1 T 2 Treatment V 0 100%NPK FYM 6.4t I AR (GRD) V 0 N 25% P 0 K 0 FYM 1.6t I WA (FP) Net returns (Rs ha -1 ) B:C ratio Net returns (Rs ha -1 ) B:C ratio T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) All kinds of costs including the fixed costs have been considered in working out the cost of cultivation above 2. Input cost (Rs. kg -1 ): FYM= 0.40 ; N= ; P 2 O 5 = 23.7 ; K 2 O= 7.42 ; VAM= Cost of produce (Rs. kg -1 ): okra fruits= 10

139 119 increase of 12 per cent in benefit cost ratio of okra as compared to its counterpart involving same P and irrigation regimes without VAM inoculation i.e. V 0 P 75% I 80%. Moreover, increase was significantly higher by 8 per cent under V 12 P 75% I 40% than treatment involving same levels of P and irrigation regimes in the absence of VAM i.e. V 0 P 75% I 40% (Table 4.17). Irrespective of VAM and irrigation levels, net returns and B:C ratio increased sharply with increased P dose from 50 to 100 per cent on soil test basis. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameters were found to be nonsignificant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 12 and 13 per cent in net returns and 10 and 11 per cent in B:C ratio, respectively over treatments involving lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatments V 0 P 100% I 80% gave significant respective increases of 9 and 19 per cent in net returns and 8 and 16 per cent in B:C ratio, respectively as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments. Further, magnitude of increase in above parameter was to the order of 7 and 16 per cent in net returns and 7 and 13 per cent in B:C ratio under V 0 P 100% I 40%, respectively over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. values of net returns and B:C ratio given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. As such, above treatments gave statistically similar performance at each of the two irrigation regimes. The same reasoning as given under plant growth parameters holds true here also. It is evident from data presented in Table 4.17 that during 2010, treatment-wise trend with respect to above parameter was similar to that found during 2009.

140 120 It can be summarized from data presented above that treatments involving VAM inoculation at varying levels of P and irrigation regimes gave higher net returns and benefit cost ratio than treatments without VAM inoculation. Further, it was noticed that treatments involving VAM at 75 per cent of soil test based recommended P dose at either of the irrigation regimes, gave the same performance as that given by 100 per cent of soil test based recommended P application. It is obvious from above that the use of VAM culture led to a saving of about 25 per cent in fertilizer P. The results of present investigation are in accordance with the findings of Kumar (2010), who has also reported higher net returns and B:C ratio of okra and wheat under combined application of VAM and soil test based recommended P in an acid Alfisol of western Himalayas. 4.4 Effect of integrated application of VAM, phosphorus and irrigation on pea Growth parameters i. Plant height In general, as a consequence of treatment application, there was a sharp increase in plant height of pea during DAS period and beyond that, increase in plant height was to a relatively less extent till the crop matured (Fig & 4.24). During , at 50 DAS treatments, V 12 P 100% I 80% and V 12 P 75% I 80% gave respective significant increases of 9 and 8 per cent, in above parameter than V 0 100%NPK FYM 12.6t I AR / GRD (Fig. 4.23). However, plant height given by V 12 P 100% I 40% and V 12 P 75% I 40% did not differ significantly than GRD. Further, differences in above parameter between treatments V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80%, between V 12 P 100% I 40% V 0 P 100% I 40% and between V 12 P 75% I 40% and V 0 P 75% I 40% were also found to be nonsignificant. Irrespective of VAM and irrigation levels, effects due to different P levels were found to be non-significant i.e. plant height given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly. A similar trend was recorded under and

141 Plant height (cm) Plant height (cm) ,0 39,6 34,7 36,7 38,7 38,0 39,0 39,1 39,0 39,2 40,8 41,0 41,3 42,8 43,1 30,0 15,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 3.03 Fig Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 50 DAS during ,0 75,0 75,7 65,1 71,4 71,4 73,4 76,7 77,1 78,5 76,1 77,7 78,4 78,1 79,6 79,6 60,0 45,0 30,0 15,0 0,0 Fig T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 3.15 Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 100 DAS during Treatment detail appears on page 32

142 122 treatments involving no-vam at varying levels of P, coupled with irrigation at 80 per cent of AWC. Similarly, treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% performed statistically similar in respect of above parameter. A similar trend was recorded under treatments involving no-vam at varying levels of P coupled with irrigation at 40 per cent of AWC. Further, irrespective of VAM and P levels, effects due to irrigation regimes were observed to be significant. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significant increases of 11, 9 and 6 per cent in above parameter, respectively than their counterpart treatments involving same levels of VAM and P i.e. V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Similarly, plant height given by V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% treatments was significantly higher by 11, 5 and 13 per cent, respectively over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. It is evident from the data depicted in Fig that at 100 DAS, the same trend as found in case of 50 DAS was observed. During , treatment-wise trend of plant height at 50 DAS and 100 DAS were similar to that observed during (Fig and 4.26). However, irrespective of VAM and P levels, treatments involving irrigation either at 80 or 40 per cent of AWC, gave the same performance statistically. During the two years of study, farmers practice (V 0 N 25% P 0 K 0 FYM 3.1t I WA ) was the tailing treatment in respect of above parameter. It can be concluded from information presented above that there was a nominal increase (8%) in plant height under VAM inoculated treatments than non-vam inoculated ones at varying levels of P and irrigation regimes. Further, treatments involving irrigation at 80 per cent of AWC gave significantly higher (14%) plant height than irrigation at 40 per cent of AWC. The greater plant height at higher irrigation regime during is attributable to the fact that roots intercept more nutrients, especially NO - 3, SO -2 4, Ca 2+ and Mg 2+ in a moist soil than a dry one, because root growth is more extensive under wet soil condition. Further, low moisture level reduced micronutrient uptake (Havlin et al. 2007). In a study involving sandy loam soil, humid condition and mung bean crop, Singh and Idani (2007) reported that root colonization with VAM increased at higher moisture levels, which in

143 Plant height (cm) ,0 45,0 44,5 37,8 38,3 41,3 42,0 43,0 44,6 45,0 43,2 44,8 45,3 45,7 46,5 46,8 30,0 15,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.27 Fig Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 50 DAS during ,0 75,0 77,5 65,7 71,6 73,2 75,4 76,8 78,3 79,1 74,6 76,7 79,0 80,0 82,1 82,7 Plant height (cm) 60,0 45,0 30,0 15,0 0, Treatment CD (P= 0.05) = 2.13 Fig Effect of integrated application of VAM, phosphorus and irrigation on plant height (cm) of pea at 100 DAS during Treatment detail appears on page 32

144 124 turn, stimulated plant growth due to more nutrient absorption which helped increase photosynthetic rate and translocation of photosynthates to the reproductive sites. Above workers also attributed increased growth and yields to higher root growth and nutrient absorption from deeper layers due to adequate availability of soil moisture at higher irrigation regime. Present results are in agreement with findings of Singh (2011), who reported higher root and shoot growth of broccoli resulting from vermicomposting (5 t ha -1 ) and irrigation management practices under an acid Alfisol of temperate climate. The reasoning for non-significant differences during at each of the two irrigation regimes is that the crop did not suffer due to moisture stress at any of the important physiological stages (flowering and pod formation), total rainfall during the growing season being more than adequate (362 mm) and the same being well distributed throughout. As such, effects due to irrigation regimes happened to be non-significant. On the other hand, higher plant height of VAM inoculated plants over non-vam inoculated ones is attributable to exploration of a larger volume of soil by mycorrhizal roots, thereby, improving nutrient and water absorption and in turn, raising plant height. A similar trend has been reported by Bahadur and Manohar (2001) under above conditions. ii. Leaf area index The data with respect to LAI of pea are depicted in Fig (s) 4.27 and During , at 50 DAS, highest and equal values of LAI were recorded under V 12 P 100% I 80%, V 12 P 75% I 80% and V 0 100%NPK FYM 12.6t I AR / GRD, all of which were found to be statistically at par with one another (Fig. 4.27). Further, above parameter values given by V 12 P 100% I 40% and V 12 P 75% I 40% did not differ significantly than GRD. The differences in respect of above parameter between V 12 P 100% I 80% and V 0 P 100% I 80% and between V 12 P 100% I 40% and V 0 P 100% I 40% were also observed to be non-significant. The treatment V 12 P 100% I 40% and V 12 P 75% I 40% gave a significant increase of 7 per cent each in above parameter than their counterparts involving same levels of P and irrigation regimes as above in the absence of VAM inoculation i.e. V 0 P 100% I 40% and V 0 P 75% I 80%. Irrespective of VAM and irrigation levels, as a consequence of P application, there was a sharp increase in leaf area index. However, difference between treatments

145 Leaf area index Leaf area index 125 1,60 1,38 1,23 1,27 1,33 1,31 1,36 1,38 1,25 1,31 1,37 1,32 1,40 1,41 1,20 1,03 0,80 0,40 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.02 Fig Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 50 DAS during ,80 2,40 2,75 2,34 2,48 2,58 2,46 2,60 2,62 2,57 2,65 2,70 2,69 2,75 2,78 2,00 1,92 1,60 1,20 0,80 0,40 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.11 Fig Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 100 DAS during Treatment detail appears on page 32

146 126 V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be nonsignificant. However, treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave significant increases of 7 and 6 per cent, respectively over V 12 P 50% I 80%. A similar trend was observed under treatments involving same VAM and P levels as above coupled with irrigation at 40 per cent of AWC. Further, treatment V 0 P 100% I 80% gave significant increases of 5 and 10 per cent in respect of above parameter over V 0 P 75% I 80% and V 0 P 50% I 80%, respectively A similar trend was observed under treatments involving same VAM and P levels as above coupled with irrigation at 40 per cent of AWC. Further, at above stage, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. At 100 DAS (during ), trend of leaf area index was found to be similar to that measured at 50 DAS (Fig. 4.28). However, irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. in case of treatments: V 12 P 100% I 80% and V 12 P 75% I 80%, LAI was found to be of same order i.e. 6 per cent, than their counterpart treatments involving same levels of VAM and irrigation regimes i.e. V 12 P 100% I 40% and V 12 P 75% I 40%. Similarly, LAI obtained under V 0 P 100% I 80% and V 0 P 75% I 80% was significantly higher i.e. 5 and 7 per cent, respectively over V 0 P 100% I 40% and V 0 P 75% I 40%. This is attributable to same reasoning as given under plant height. Irrespective of VAM and irrigation levels, effects due to different P levels were found to be non-significant i.e. LAI given by treatments V 12 P 100% I 80% and V 12 P 75% I 80% did not differ significantly. A similar trend was recorded under treatments involving no-vam at varying levels of P coupled with irrigation at 80 per cent of AWC. Similarly, treatments V 12 P 100% I 40% and V 12 P 75% I 40% performed statistically similar in respect of above parameter. A similar trend was recorded under treatments involving no-vam at varying levels of P coupled with irrigation at 40 per cent of AWC. Further, during , values of LAI obtained under various treatments at 60 and 100 DAS, gave the same trend as observed during 2009 (Fig 4.29 & 4.30).

147 Leaf area index Leaf area index 127 1,60 1,49 1,26 1,31 1,36 1,36 1,41 1,43 1,29 1,34 1,39 1,36 1,42 1,45 1,20 1,06 0,80 0,40 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.07 Fig Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 50 DAS during ,20 2,80 3,00 2,50 2,64 2,74 2,62 2,75 2,78 2,73 2,81 2,86 2,86 2,91 2,92 2,40 2,00 2,00 1,60 1,20 0,80 0,40 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 0.09 Fig Effect of integrated application of VAM, phosphorus and irrigation on leaf area index of pea at 100 DAS during Treatment detail appears on page 32

148 128 It can be concluded that the highest LAI was found in case of VAM involving treatments, even though they were statistically at par with GRD. However, VAM inoculation coupled with P gave significantly higher (6%), LAI than non-vam inoculated ones at different irrigation regimes. The better growth of VAM inoculated pea plants over non-vam inoculated ones is attributable to enhanced activity of cytokinin (a growth promoter), of which P is the major component and which promotes leaf growth through enhanced cell division and cell expansion. A similar explanation has been given by Li et al. (1994). Results are in conformity with findings of Osonubi (1994), who reported significantly higher leaf area (18.4 m 2 plant -1 ) in VAM inoculated maize plants under temperate situation involving an Alfisol having ph 6.8. Edathil et al. (1996) have also reported higher (61%) leaf area of tomato due to combined application of VAM and P in P deficient soils under humid conditions. iii. Periodic dry matter accumulation Effect of various treatments on dry matter accumulation is depicted in Fig. (s) At 50 DAS ( and ), various treatments did not influence dry matter accumulation significantly barring farmers practice, which was found significantly inferior to all treatments (Fig and 4.33). At 100 DAS, V 12 P 100% I 80% and V 12 P 100% I 40% gave significantly higher i.e. 7 and 6 per cent dry matter accumulation, respectively than V 0 100%NPK FYM 12.6t I AR / GRD (Fig. 4.32). However, GRD exhibited an increase by 6 per cent each in above parameter than V 12 P 100% I 40% and V 121 P 75% I 40%. However, differences between V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80%, between V 12 P 100% I 40% and V 0 P 100% I 40% and between V 12 P 75% I 40% and V 0 P 75% I 40% were observed to be nonsignificant. Further, treatments involving irrigation at 80 per cent of AWC, at varying levels of P in the presence and absence of VAM inoculation, gave significantly higher dry matter accumulation than irrigation at 40 per cent of AWC. In case of treatments: V 12 P 100% I 80% and V 12 P 75% I 80%, above parameter was found to be of the same order i.e. 12 per cent, significantly higher than V 12 P 100% I 40% and V 12 P 75% I 40%. Similarly, magnitude of

149 Dry matter accumulation (g plant -1 ) Dry matter accumulation (g plant -1 ) 129 6,00 4,00 4,32 3,99 4,12 4,32 4,02 4,26 4,28 4,00 4,32 4,28 3,92 4,32 4,35 2,00 1,43 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = NS Fig Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of pea at 50 DAS during ,00 6,50 5,22 5,69 6,20 5,71 6,32 6,45 6,20 6,46 6,92 6,72 7,12 7,24 2,65 0,00 Fig T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = 1.22 Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of pea at 100 DAS during Treatment detail appears on page 32

150 Dry matter accumulation (g plant -1 ) Dry matter accumulation (g plant -1 ) 130 6,00 4,00 4,26 3,88 4,08 4,32 3,84 4,04 4,25 3,42 4,15 4,24 3,46 4,08 4,19 2,00 1,52 0,00 Fig T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment CD (P= 0.05) = NS Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of pea at 50 DAS during ,00 6,82 5,10 5,82 6,22 5,69 6,24 6,32 5,94 6,42 6,78 6,43 7,16 7,25 2,91 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 CD (P= 0.05) = 0.30 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on dry matter accumulation (g plant -1 ) of pea at 100 DAS during Treatment detail appears on page 32

151 131 increase was 13 and 12 per cent under V 0 P 100% I 80% and V 0 P 75% I 80%, respectively than their counterpart treatments involving same VAM and P levels at 40 per cent of AWC i.e. V 0 P 100% I 40% and V 0 P 75% I 40%. The same reasoning as given under plant height parameter holds true here also. Further, at 100 DAS, during , values of dry matter accumulation obtained under various treatments (at 50 DAS stage) gave the same trend as observed during the previous year (Fig 4.34). It can be inferred from above that VAM inoculated plants gave marginally higher dry matter accumulation than non-vam inoculated ones at varying levels of P and irrigation. Further, dry matter accumulation obtained under treatments involving irrigation at 80 per cent of AWC was significantly higher (13%) than treatments with 40 per cent of AWC at varying levels of VAM and P. Higher amount of dry matter accumulation in VAM inoculated plants is attributable to more efficient absorption, utilization and assimilation of soil moisture. Above processes maintained stomata in open condition and enhanced dry matter production. The same reasoning is given by Bethlenfalvay et al. (1988) for enhanced LAI in their study. Davies and Linderman (1991) attributed above increase, to improved water relations resulting from enhanced P nutrition. The present results are in agreement with findings of Kongpun et al. (2011), who observed 25 per cent higher dry matter production in cowpea under combined application 64 kg P 2 O 5 ha -1 and VAM inoculation over 32 kg P 2 O 5 ha -1 + VAM culture in a field experiment involving an acid soil categorized as low in available P Yield contributing characters and yields Yield contributing characters i. Pod length The data presented in Table 4.18 revealed that none of the treatments influenced above parameter significantly during the two years of experimentation. ii. Pod girth Covering all the pickings during the two years of experimentation, the impact of different treatments on pod girth was found to be non-significant (Table 4.18). Overall, the pod girth was numerically higher in treatments involving VAM inoculation

152 132 Table 4.18 Effect of integrated application of VAM, phosphorus and irrigation on pod length (cm) and pod (cm) girth of pea during crop growth Pod length Pod girth Treatment 1 st picking 3 rd picking 1 st picking 3 rd picking T 1 V 0 100%NPK FYM 12.6t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) NS NS NS NS NS NS NS NS Treatment detail appears on page 32

153 133 coupled with P and irrigation as compared to non-vam inoculated ones coupled with VAM and irrigation. iii. Average pod weight Average pod weight data obtained under various treatments are presented in Table The data revealed that various treatments influenced above parameter significantly during the two years of study. During , at 1 st picking, maximum and significant increase in average fruit weight was found under V 12 P 100% I 80% followed by V 12 P 75% I 80%. Both the above treatments exhibited an increase of 8 per cent each over V 0 100%NPK FYM 12.6t I AR / GRD. However, V 12 P 100% I 40% and V 12 P 75% I 40% did not influence above parameter significantly, over GRD (Table 4.19). The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significantly higher average pod weight i.e. 7, 8 and 11 per cent as compared to V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. However, average fruit weight given by V 12 P 100% I 40% and V 0 P 100% I 40% treatments did not differ significantly than V 12 P 75% I 40% and V 0 P 75% I 40%. But, treatment V 12 P 50% I 40% exhibited an increase of 11 per cent in respect of average fruit weight than its non-vam counterpart involving the same P and irrigation levels i.e. V 0 P 50% I 40%. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. average pod weight given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. The same reasoning as given under plant growth parameters holds true here also. Irrespective of VAM and irrigation levels, effects due to different P levels were found to be non-significant.

154 134 Table 4.19 Effect of integrated application of VAM, phosphorus and irrigation on pod number per kg and average pod weight (g) during crop growth Pod number kg -1 Average pod weight Treatment 1 st picking 3 rd picking 1 st picking 3 rd picking T 1 V 0 100%NPK FYM 12.6t I AR (GRD) Pooled Pooled Pooled Pooled T 2 V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 32

155 135 During (at 1 st picking), treatment-wise trend in respect of above parameter was found similar to that obtained during Further, statistical pooling of pod weight data for the two years of study gave the same trend as that obtained during and (Table 4.19). During and , data on above parameter obtained at 3 rd picking gave the same trend as observed during the 1st picking of (Table 4.19). It can be summed up from information presented above that treatments involving VAM inoculation gave a significant increase of 8 per cent in above parameter than non- VAM inoculated ones at varying levels of P and irrigation. Higher pod weight under VAM involving treatments might be because of higher availability of nutrients and water. The improvement in yield attributes could also be partially because of production of growth substances like indole acetic acid and gibberalic acid by VAM, which in turn, might have increased the availability and uptake of nutrients through mycorrhizal roots. Bahadur and Manohar (2001) also observed higher fruit weight of okra under combined use of VAM coupled with P under neutral ph soil rating high in available P under semi-arid climatic condition. iv. Pod number per kg It is apparent from data presented in Table 4.19 that during the 2 year study period ( and ) different treatments influenced above parameter significantly at different pickings. During , at 1 st picking, lowest and equal pod number per kg were recorded under V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, all of which were found to be statistically at par with V 0 100%NPK FYM 12.6t I AR / GRD. Moreover, values of above parameter obtained under V 12 P 100% I 40%, V 12 P 75% I 40% and GRD treatments did not differ significantly. Further, differences between treatments V 12 P 100% I 80% and V 0 P 100% I 80%, between V 12 P 75% I 80% and V 0 P 75% I 80%, between V 12 P 100% I 40% and V 0 P 100% I 40% and between V 12 P 75% I 40% and V 0 P 75% I 40% were also found to be non-significant. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. pod number per kg given by treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% did not differ significantly than V 12 P 100% I 40%, V 12 P 75% I 40% and

156 136 V 12 P 50% I 80%. Further, differences between V 0 P 100% I 80% and V 0 P 100% I 40%, between V 0 P 75% I 80% and V 0 P 75% I 40% and between V 0 P 50% I 80% and V 0 P 50% I 40% were also observed to be non-significant. The same reasoning as given under plant growth parameters holds true here also. Irrespective of VAM and irrigation levels, effects due to different P levels were found to be non-significant. During at 1 st picking, significantly less pod number per kg i.e. 11 per cent in each case were noticed under V 12 P 100% I 80% and V 12 P 75% I 80% than GRD (Table 4.19). Further, significant decreases of 8 per cent in each of the 2 treatments i.e. V 12 P 100% I 40% and V 12 P 75% I 40%, were found in above parameter over GRD. The treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave significantly lower pod number per kg i.e. 8 and 11 per cent, respectively than their counterparts involving same levels of P and irrigation regimes as above without VAM inoculation i.e. V 0 P 100% I 80% and V 0 P 75% I 80%. Moreover, V 12 P 75% I 40% gave 8 per cent less number of pods per kg as compared to V 0 P 75% I 40%. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be nonsignificant. Likewise, irrespective of VAM and irrigation levels, effects due to different P levels were found to be non-significant. It is obvious from data presented in Table 4.23 that pooled statistical analysis in respect of above parameter, gave the same trend as observed during During and , at 3 rd picking, treatment-wise trend in respect of above parameter was found similar to that obtained under 1 st picking of the year (Table 4.19). The reason for less pod number per kg in case of VAM involving treatments under varying levels of P is obvious i.e. increase in pod weight, led to a decrease in number of pods per kg in case of above treatments. Further, mycorrhizal fungi explored a larger volume of soil through their mycelial growth, thereby, enabling plant root system to absorb a higher amount of nutrients and water from the soil. It led to enhanced pod characteristics of pea.

157 Yields Green pod yield data under various treatments are presented in Table The different treatments influenced above parameter significantly during the two years of study. During , highest green pod yield was recorded under V 12 P 100% I 80% followed by V 12 P 75% I 80% and V 0 100%NPK FYM 12.6t I AR / GRD, all of which were found to be statistically at par with one another. The difference in pod yield obtained under V 12 P 100% I 40% and GRD was also found to be non-significant (Table 4.20). It is further noticed that V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significantly higher i.e. 11, 18 and 20 per cent green pod yield, respectively than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Moreover, significant increases of 17, 12 and 10 per cent in above parameter were obtained under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 75% I 40% than treatments involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, as a consequence of P application, there was a sharp increase in leaf area index (Table 4.20). However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 12 and 18 per cent, respectively over lower level (50%P) of applied P treatments i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant increases of 11 and 16 per cent over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Further, magnitude of increase in above parameter was to the order of 9 and 15 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Further, a cursory look at data presented in Table 4.20 reveals that, irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave significant respective

158 138 Table 4.20 Effect of integrated application of VAM, phosphorus and irrigation on green pod yield (q ha -1 ) of pea Treatment T 1 V 0 100%NPK FYM 12.6t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 32

159 139 increases of 8, 15 and 18 per cent than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. Similarly, the magnitude of increase was 13, 8 and 8 per cent under V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%, respectively over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. This is attributable to same reasoning as given under plant height parameters. During , highest green pod yield was recorded under V 12 P 100% I 80% followed by V 12 P 75% I 80% and V 0 100%NPK FYM 12.6t I AR / GRD, all of which were found During , green pod yield was recorded highest under V 12 P 100% I 80% followed by V 12 P 100% I 40% and GRD, all of which were found to be statistically at par with one another. The green pod yield given by V 12 P 100% I 80% treatment did not differ significantly than its non-vam counterpart, involving same P and irrigation levels i.e. V 0 P 100% I 80%. However, treatments V 12 P 75% I 80% and V 12 P 50% I 80% gave significant increases of 9 and 14 per cent, respectively over their non-vam inoculated counterparts, involving same P and irrigation levels i.e. V 0 P 75% I 80% and V 0 P 50% I 80%. In case of P and irrigation factors, treatment-wise trend with respect to above parameter was similar to that found during The yield data presented above clearly suggest that combined application of VAM, P and irrigation may enhance pea yield, on an average, by 14 per cent and could effectively meet P need of crop by about 25 per cent. The application of VAM enhanced yield attributes (average pod weight and to some extent pod length) of pea, which consequently, resulted in higher yield of above crop. Higher yield obtained in case of VAM inoculated plants is attributable to a greater utilization of nutrients particularly P by plants as a result of their efficient solubilisation and mobilisation by VAM fungi. In a study involving an acid Alfisol, wet temperate conditions and okra crop, Kumar (2010) reported that 100 per cent soil test based P dose gave statistically the same yield as given by 75 per cent soil test based P dose coupled with VAM inoculation. Above report implies a saving in fertilizer P to the tune of about 25 per cent. Suri et al. (2010) working with soybean crop under same conditions as above (Palam Valley), also obtained a saving in fertilizer P to the extent of about 25 per cent.

160 Agronomic efficiency of P based on response ratio Above parameter was computed to evaluate biological efficiency of phosphorus applied under various treatments. The relevant information is presented in Table During , an impressive increase in agronomic efficiency of P/ P response ratio due to use of mycorrhizal biofertilizer (VAM) in concerned treatments was obtained. The treatment V 0 100%NPK FYM 12.6t I AR / GRD gave comparatively lower response ratio due to higher nutrient input. Irrespective of VAM and irrigation levels, treatment involving 50 per cent of soil test based recommended P dose gave a higher response ratio. However, in pursuance of the law of diminishing returns, it decreased as the P levels increased, with every additional increment of P. Irrespective of P and irrigation regimes, treatments involving VAM inoculation gave significantly higher P response ratio to those not involving VAM-inoculation. The treatments V 12 P 50% I 80% and V 12 P 75% I 80% gave 60 and 45 per cent higher P response ratio, respectively than their non-vam counterparts involving same levels of P and irrigation regimes i.e. V 0 P 50% I 80% and V 0 P 75% I 80%. However, differences between V 0 P 100% I 80% and V 0 P 100% I 80% treatments were found to be non-significant, probably due to lower efficiency of VAM fungi at higher P levels. The data of current study depicted in Fig. (s) 4.43 & 4.44 are also supportive of above statement. Further, V 12 P 50% I 40% and V 12 P 75% I 40% gave respective increases of 35 and 31 per cent in above parameter as compared to V 0 P 50% I 40% and V 0 P 75% I 40%. Irrespective of VAM and irrigation levels, a decrease in P response ratio was observed with increasing P levels from 50 to 100 per cent of recommended P dose on soil test basis. The values of P response ratio given by treatment V 12 P 50% I 80 were 28 and 61 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 100% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 15 and 27 per cent under V 12 P 50% I 40% treatment over V 12 P 75% I 40% and V 12 P 100% I 40% treatments. A similar trend was observed in case of treatments involving no-vam inoculation at each of the two irrigation regimes (80 or 40 per cent of AWC) coupled with different P levels.

161 141 Table 4.21 Effect of integrated application of VAM, phosphorus and irrigation on P response ratio (kg yield kg -1 P) of pea Treatment Yield (kg ha -1 ) Pooled P applied as P response P applied as P response P response Yield P 2 O 5 ratio P (kg ha -1 2 O 5 ratio ratio ) (kg ha -1 ) (kg yield kg -1 P) (kg ha -1 ) (kg yield kg -1 P) (kg yield kg -1 P) T 1 V 0 100%NPK FYM 12.6t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 32

162 142 Irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. values of P response ratio given by treatments V 12 P 75% I 80% and V 12 P 50% I 80% were 32 and 48 per cent significantly higher, respectively over V 12 P 75% I 40% and V 12 P 50% I 40%. Further, magnitude of increase in above parameter was to the order of 35 per cent under V 12 P 100% I 40% as compared to V 0 P 100% I 40%. The same reasoning as given under plant growth parameters holds true here also. The values of P response ratio obtained during gave the same trend as obtained during But, irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. Further, pooled statistical analysis of data covering the 2 years of investigation also gave an identical trend (Table 4.21). It can be inferred from the data presented above that VAM inoculated plants coupled with P application at varying levels of irrigation, gave higher (30%) P response ratio than non-vam inoculated ones. Further, treatments involving irrigation at 80 per cent of AWC gave significantly higher P response ratio (37%) than irrigation at 40 per cent of AWC. The general trend of response ratio data can be explained through the law of diminishing returns (Voisin 1962). However, a higher response ratio in case of VAM involving treatments under varying levels of P is obviously the outcome of higher pea productivity. Under matching conditions, Dhinakaran and Savithri (1997), found an increase of 32 per cent in P use efficiency under VAM inoculation kg P 2 O 5 ha - 1 (GRD) treatment, which is attributable to above reasons Plant water status i. Relative leaf water content (RLWC) It is apparent from data presented in Table 4.22 that RLWC increased sharply in various treatments at different stages of crop growth. During , at 50 DAS (0700 hrs), maximum and significant RLWC values i.e. 2 per cent higher in each case, were found under V 12 P 100% I 80% and V 12 P 75% I 80% over V 0 100%NPK FYM 12.6t I AR / GRD. Likewise, in case of treatments V 12 P 100% I 40% and V 12 P 75% I 40%, RLWC was found to be of

163 143 Table 4.22 Effect of integrated application of VAM, phosphorus and irrigation on relative leaf water content (%) during pea crop growth 60 DAS 100 DAS Treatment V T 0 100%NPK FYM 12.6t 1 I AR (GRD) V T 0 N 25% P 0 K 0 FYM 3.1t I WA 2 (FP) Morning Afternoon Morning Afternoon Morning Afternoon Morning Afternoon Pooled T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 32

164 144 same order i.e. 2 per cent higher than GRD. It is further revealed that each of the three treatments viz. V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave marginal increases of 2 per cent each in above parameter than their non-vam counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Moreover, respective increases of 2 per cent in each of the three treatments i.e. V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% were found in above parameter than V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40% (Table 4.22). Irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose did not differ significantly in respect of above parameter than those involving 75 and 50 per cent of P dose (both at morning and afternoon) during the two years of investigation. But, RLWC increased sharply with increasing P levels from 50 to 100 per cent P application based on soil test. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. As such, effects due to irrigation regimes were observed to be non-significant. The same reasoning as given under plant growth parameters holds good here also. At above crop stage, in the afternoon hours, values of RLWC obtained under various treatments followed the same trend as that obtained during the morning hours. However, differences in RLWC values were more prominent during afternoon hours. The maximum and significant values i.e. 3 per cent each in above parameter were observed under V 12 P 100% I 80% treatment followed by V 12 P 75% I 80%, respectively than GRD. Likewise, RLWC given by V 12 P 100% I 40% and V 12 P 75% I 40% was higher by 3 per cent in each case over GRD (Table 4.22). It is further noticed that treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave significant respective increases of 3 per cent in each case in above parameter than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Moreover, significantly higher i.e. 3 per cent each case, RLWC were recorded under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, respectively in comparison with V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. In case of P and irrigation factors, treatment-wise trend with respect to above parameter was similar to that found during morning hours.

165 145 Further, at 100 DAS ( ), trend of RLWC was similar to that observed at 50 days stage covering both the morning as well as afternoon hours. Just a glance at the data presented in Table 4.22 shows that during , values of RLWC obtained under various treatments at two times in a day gave the same trend as found during the previous year i.e On the basis of information presented above, it can be summarized that overall, integrated application of VAM, P and irrigation influenced relative leaf water content substantially i.e. 28 per cent over the non-vam counterpart. The treatments involving irrigation either at 80 or 40 per cent of AWC at varying levels of P, with and without VAM inoculation, did not influence above parameter significantly. The probable reason for high RLWC in treatments involving VAM inoculation as compared to non-vam inoculated ones (at similar levels of P and irrigation regimes), is that the mycorrhizal plants are able to maintain higher tissue water content, which might impart a greater drought resistance power to plants. Farahani et al. (2008), who conducted a pot experiment, have also reported higher RLWC in coriander under integrated application of VAM and P under drought stress condition. ii. Xylem water potential (XWP) The data on above parameter are presented in Table During , at morning time (0700 hrs), highest and significant i.e. 33 and 27 per cent values of XWP were found under V 12 P 100% I 80% followed by V 12 P 75% I 80%, respectively than V 0 100%NPK FYM 12.6t I AR / GRD. Similarly, each of the 2 treatments viz. V 12 P 100% I 40% and V 12 P 75% I 40% gave significant increases of 27 per cent each in above parameter than GRD. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave respective increases of 22, 21 and 18 per cent in above parameter than their non-vam counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Moreover, each of the three treatments viz., V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, gave 19, 19 and 27 per cent increases in above parameter than V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40% (Table 4.23).

166 146 Table 4.23 Effect of integrated application of VAM, phosphorus and irrigation on xylem water potential (k Pa) during pea crop growth Treatment 60 DAS 100 DAS Morning Afternoon Morning Afternoon Morning Afternoon Morning Afternoon T 1 V 0 100%NPK FYM 12.6t I AR (GRD) T 2 V 0 N 25% P 0 K 0 FYM 3.1t I WA (FP) T 3 V 0 P 50% I 40% T 4 V 0 P 75% I 40% T 5 V 0 P 100% I 40% T 6 V 12 P 50% I 40% T 7 V 12 P 75% I 40% T 8 V 12 P 100% I 40% T 9 V 0 P 50% I 80% T 10 V 0 P 75% I 80% T 11 V 0 P 100% I 80% T 12 V 12 P 50% I 80% T 13 V 12 P 75% I 80% T 14 V 12 P 100% I 80% CD (P=0.05) Treatment detail appears on page 32

167 147 During the afternoon (1400 hrs), various treatments gave the same trend as observed during morning (0700 hrs); however, differences amongst the treatments were wider. The highest and significant increases (25% in each case) in above parameter was recorded under V 12 P 100% I 80% followed by V 12 P 75% I 80%, respectively than GRD. Further, both V 12 P 100% I 40% and V 12 P 75% I 40% gave equal and significant (25 per cent in each case), increase in XWP over GRD. The XWP obtained in case of V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, was 18, 22 and 20 per cent higher and significant than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Likewise, values of above parameter given by V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, were 23, 25 and 21 per cent higher and significant than their non-vam counterparts involving same levels of P and irrigation regimes i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. At both the times of the day, irrespective of VAM and irrigation levels, treatments involving 100 per cent of soil test based recommended P dose, did not differ significantly in respect of above parameter than those involving 75 and 50 per cent of P dose during the two years of investigation. But, XWP increased sharply with increasing P levels from 50 to 100 per cent of recommended P dose based on soil test. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be non-significant i.e. differences between V 12 P 100% I 80% and V 12 P 100% I 40%, between V 12 P 75% I 80% and V 12 P 75% I 40%, between V 0 P 100% I 80% and V 0 P 100% I 40% and between V 0 P 75% I 80% and V 0 P 75% I 40% were found to be non-significant. As such, effects due to irrigation regimes were observed to be non-significant. The same reasoning as given under plant growth parameters holds good here also. A random look at data presented in Table 4.23 revealed that values of XWP obtained under various treatments gave the same trend as obtained during Further, at 100 DAS, treatment-wise trend with respect to above parameter was similar to that obtained during 50 DAS covering both the morning and afternoon hours. On the basis of information presented above, it can be summarized that overall, integrated application of VAM, P and irrigation influenced xylem water potential, on an average, by 27 per cent. The treatments involving irrigation either at 80 or 40 per cent of

168 148 AWC at varying levels of P with and without VAM inoculation, did not influence above parameter significantly. also. iii. The same reasoning as given under relative leaf water content is applicable here Water use efficiency (WUE) The information pertaining water use efficiency as affected by various treatments evaluated in pea experiment is given in Table During , highest WUE was observed under V 12 P 100% I 40% followed by V 12 P 75% I 40%, both of which gave significantly higher values i.e. 28 and 17 per cent in above parameter, respectively over V 0 100%NPK FYM 12.6t I AR / GRD. However, the values of above parameter given by V 12 P 100% I 80%, V 12 P 75% I 80% and GRD did not differ significantly. The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave significantly higher i.e. 11, 19 and 20 per cent WUE, respectively than V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Moreover, significant respective increases of 17, 12 and 11 per cent in above parameter were observed in case of V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% as compared to V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in WUE was recorded with increasing P levels from 50 to 100 per cent recommended on soil test basis. However, differences between treatments V 12 P 100% I 80% and V 12 P 75% I 80% and between V 12 P 100% I 80% and V 12 P 75% I 80% in respect of above parameter were found to be non-significant. It signifies economy of fertilizer P by about 25 per cent through use of mycorrhizal fungi. Further, treatments involving 100 per cent of soil test based recommended P dose i.e. V 12 P 100% I 80% and V 12 P 100% I 40% gave significant increases of 12 and 22 per cent, respectively over lower level (50%P) of applied P i.e. V 12 P 50% I 80% and V 12 P 50% I 40%. Similarly, treatment V 0 P 100% I 80% gave significant increases of 10 and 22 per cent as compared to V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. Further, magnitude of increase in above parameter was to the order of 5 and 16 per cent under V 0 P 100% I 40% over V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. It is notable that during 2010, treatment-wise trend in respect of above parameter was similar to that found during 2009 (Table 4.24).

169 149 Table 4.24 Effect of integrated application of VAM, phosphorus and irrigation on water use efficiency (kg ha -1 mm -1 ) of pea crop Treatment Yield (kg ha -1 ) TWU Yield TWU (mm) (kg ha -1 ) (mm) WUE (kg ha -1 mm -1 ) WUE (kg ha -1 mm -1 ) (1) (2) (1 2) (1) (2) (1 2) T 1 V 0100%NPK FYM 12.6t I AR(GRD) (5) (3) 26.7 T 2 V 0N 25%P 0K 0FYM 3.1t I WA (FP) (3) (2) 17.0 T 3 V 0 P 50% I 40% (3) (2) 23.0 T 4 V 0 P 75% I 40% (3) (2) 25.8 T 5 V 0 P 100% I 40% (3) (2) 28.5 T 6 V 12 P 50% I 40% (3) (2) 26.3 T 7 V 12 P 75% I 40% (3) (2) 28.3 T 8 V 12 P 100% I 40% (3) (2) 30.0 T 9 V 0 P 50% I 80% (5) (3) 21.3 T 10 V 0 P 75% I 80% (5) (3) 23.8 T 11 V 0 P 100% I 80% (5) (3) 26.0 T 12 V 12 P 50% I 80% (5) (3) 24.2 T 13 V 12 P 75% I 80% (5) (3) 26.0 T 14 V 12 P 100% I 80% (5) (3) 27.6 CD (P=0.05) *Figures within parentheses show the number of irrigations applied (50 mm each) ; Effective rainfall (mm): During = 173 mm & during = 300 mm); Total water used= water applied through irrigation (mm) + effective rainfall (mm)

170 150 Irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. WUE given by treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% increased significantly by 22, 14 and 11 per cent, respectively over V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%. Similarly, the magnitude of increase was 15, 20 and 21 per cent under V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%, respectively over V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% (Table 4.24). It is evident from data presented in Table 4.24 that during , treatmentwise trend with respect to above parameter was similar to that found during On the basis of information presented above, it can be summarized that VAM inoculation involving treatments gave 19 per cent higher water use efficiency at varying levels of applied P and irrigation regimes. Further, treatments involving irrigation at 80 per cent of AWC gave significantly higher WUE (13%) than irrigation at 40 per cent of AWC. Needless to say that VAM inoculation results into the establishment of great fungal hyphal network, which through the processes of solubilisation and mobilisation enhances availability of almost all essential nutrients especially P, which obviously contributes to higher WUE to a great extent. The similar findings as above were reported by Kothari et al. (1990) and Al-Karaki (1998) with maize and wheat grown under warm humid climate and calcareous soil. They attributed the responses obtained, following VAM inoculation to same logic as given above Root parameters i. Maximum rooting length Maximum rooting length data of experiment recorded at maximum flowering stage (90 DAS) are depicted in Fig. (s) 4.35 and During , V 12 P 100% I 80% and V 12 P 75% I 80% gave respective increases of 12 and 10 per cent in above parameter than V 0 100%NPK FYM 12.6t I AR / GRD. Further, increases in above parameter were to the order of 5 and 2 per cent under V 12 P 100% I 40% and V 12 P 75% I 40% treatments, respectively over GRD (Fig. 4.35). The maximum rooting length found in case of V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments was 11, 16 and 5 per cent higher, respectively than their non-

171 Maximum rooting length (cm) Maximum rooting length (cm) ,0 16,1 13,6 14,7 15,9 14,6 16,4 16,9 14,3 15,2 16,3 15,0 17,7 18,1 10,0 8,4 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting length (cm) of pea during ,0 16,4 13,1 14,3 15,2 14,2 16,1 16,6 13,6 14,7 15,7 15,0 16,8 17,4 10,0 8,7 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on maximum rooting length (c m) of pea during Treatment detail appears on page 32

172 152 V 0 100%NPK FYM 10t I AR / GRD Vs V 12 P 100% I 80% V 12 P 75% I 40% Vs V 12 P 100% I 40% V 0 100%NPK FYM 10t I AR / GRD Vs V 12 P 100% I 40% V 12 P 50% I 40% Vs V 12 P 50% I 40% Plate 4.3. Response of pea roots to integrated application of VAM, P and irrigation during 2009

173 153 VAM counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, increases of 6, 12 and 7 per cent were observed under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%, respectively over treatments involving same levels of P and irrigation regimes in the absence of VAM culture i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, rooting depth increased with each additional increment of P dose. The values of above parameter given by treatment V 12 P 100% I 80 were 2 and 21 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 7 and 14 per cent under V 0 P 100% I 80% treatment in comparison with V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave respective increases of 7, 8 and 3 per cent in respect of above parameter than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. Similarly, magnitude of increase was 3, 3 and 5 per cent in case of V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80% over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Above trend is attributable to same reasoning as given under plant growth parameters. During , maximum rooting length obtained under various treatments gave the same trend as that obtained in the previous year (Fig. 4.36). But, treatments involving irrigation at 80 per cent of AWC at varying levels of P, with and without VAM inoculation, gave almost similar values of above parameter than treatments involving irrigation at 40 per cent of AWC, thereby, implying that irrigation regimes did not influence above parameter. On the basis of information presented above, it can be summarized that VAM inoculation enhanced pea maximum rooting length by 9 per cent at varying P and irrigation levels. Further, treatments involving irrigation at 40 per cent of AWC gave 7 per cent longer roots than irrigation at 80 per cent of AWC. Song (2005) reported that soil inoculation with VAM increased maximum rooting length. Above trend is attributable to increased number of higher order laterals in VAM

174 154 inoculated treatments as compared to non-vam inoculated ones. In pot experiments with maize and tomato involving low available P soils, Kothari et al. (1990) and Edathil et al. (1996) observed 17 and 53 per cent respective increases in maximum rooting length under combined use of VAM and P than absolute control. ii. Root Volume The data on above parameter are depicted in Fig.(s) 4.37 and During , V 12 P 100% I 80% and V 12 P 75% I 80% gave respective increases of 17 and 15 per cent in above parameter than V 0 100%NPK FYM 12.6t I AR / GRD. Further, increases in above parameter under V 12 P 100% I 40% and V 12 P 75% I 40% were to the tune of 8 and 6 per cent, respectively over GRD (Fig. 4.37). The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments gave 18, 24 and 15 per cent higher root volume, respectively than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 19, 31 and 38 per cent in above parameter were noticed in case of V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% in comparison with V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40% treatments. Irrespective of VAM and irrigation levels, an increase in root volume was observed with increasing P levels from 50 to 100 per cent of soil test based recommended P dose. The values of above parameter given by treatment V 12 P 100% I 80 were 2 and 19 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 7 and 16 per cent under V 0 P 100% I 80% treatment in comparison with V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. Irrespective of VAM and P levels, effects due to irrigation regimes were found to be significant i.e. root volume data given by V 12 P 100% I 80% and V 12 P 75% I 80% gave respective increases of 8 and 9 per cent than V 12 P 100% I 40% and V 12 P 75% I 40%. Similarly, magnitude of increase was 9, 15 and 10 per cent in case of V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%,

175 Root volume (ml) Root volume (ml) ,0 22,2 22,6 20,0 19,3 12,6 14,0 15,6 17,6 19,3 20,4 20,9 16,5 17,9 19,1 19,0 10,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of pea during ,0 20,0 19,6 13,1 15,0 16,3 18,1 16,9 19,0 19,6 16,1 17,3 18,5 17,8 19,9 20,8 10,0 0,0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root volume (ml) of pea during Treatment detail appears on page 32

176 156 respectively over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Above trend is attributable to same reasoning as given under plant height parameter. During , root volume obtained under various treatments gave the same trend as that obtained during the previous year i.e (Fig. 4.38). But, treatments involving irrigation at 80 per cent of AWC at varying levels of P with and without VAM inoculation gave almost similar values of above parameter than treatments involving irrigation at 40 per cent of AWC, thereby, implying that irrigation regimes did not influence above parameter. Based on information presented above, it can be summarized that VAM inoculation enhanced root volume by 23 per cent at varying P and irrigation levels. Further, treatments involving irrigation at 40 per cent of AWC gave 12 per cent higher root volume than irrigation at 80 per cent of AWC. The higher root volume values are attributable to extension of crop root system into soil profile by way of development of higher order laterals through ramification of fungal hyphae associated with it. Present results are in agreement with findings of Singh (2011), who found higher root volume of broccoli resulting from vermicomposting (5 t ha -1 ) and irrigation management practices under an acid Alfisol of temperate climate. iii. Root dry weight The information on above parameter covering the two years of experimentation is depicted in Fig (s) 4.39 and During , treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave 10 and 8 per cent higher root dry weight, respectively than V 0 100%NPK FYM 12.6t I AR / GRD. Further, respective increases in above parameter under V 12 P 100% I 40% and V 12 P 75% I 40% were to the order of 3 and 2 per cent in comparison with GRD (Fig. 4.41). Moreover, treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% gave 8, 11 and 9 per cent higher root dry weight, respectively than their non-vam counterparts involving same P and irrigation levels i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, values of above parameter found under V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% were to the tune of 20, 25 and 20 per cent, respectively than V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%.

177 Dry root weight (g) Dry root weight (g) 157 1,5 1 1,24 0,94 1,02 1,07 1,13 1,27 1,28 1,15 1,21 1,26 1,25 1,34 1,36 0,75 0,5 0 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of pea during ,50 1,00 1,25 0,84 1,03 1,14 1,22 1,21 1,30 1,34 1,07 1,18 1,25 1,24 1,32 1,36 0,50 0,00 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root dry weight (g) of pea during Treatment detail appears on page 32

178 158 Irrespective of VAM and irrigation levels, an increase in root dry weight was observed with increasing P levels from 50 to 100 of soil test based recommended P dose. The values of above parameter given by treatment V 12 P 100% I 80 were 2 and 9 per cent higher in comparison with V 12 P 75% I 80% and V 12 P 50% I 80% treatments, respectively. Likewise, magnitude of increase was to the extent of 4 and 10 per cent under V 0 P 100% I 80% treatment in comparison with V 0 P 75% I 80% and V 0 P 50% I 80% treatments, respectively. A similar trend was observed in case of treatments involving irrigation at 40 per cent of AWC in the presence and absence of VAM application at varying levels of applied P. Irrespective of VAM and P levels, treatments involving irrigation at 80 per cent of AWC showed an edge over irrigation at 40 per cent of AWC. Further, V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave respective increases of 5, 6 and 11 per cent than V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. Similarly, the magnitude of increase was 18, 19 and 11 per cent under V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%, respectively over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. During , treatment wise trend in respect to above parameter gave the same pattern as that obtained during (Fig. 4.40). On the basis of information presented above, it can be summarized that VAM inoculation enhanced pea root dry weights by 18 per cent at varying P and irrigation levels. Further, treatments involving irrigation at 40 per cent of AWC gave 19 per cent higher root dry weight than irrigation at 80 per cent of AWC. The same reasoning as given under maximum rooting length and root volume holds true here also due to obvious reason. The present results are in conformity with findings of Rabie and Humiany (2004), who observed increased root dry weights in cowpea under similar soil and climatic conditions due to application of P coupled with VAM. iv. Root weight density The information on above parameter is depicted in Fig.(s) 4.41 and During , treatments V 12 P 100% I 80% and V 12 P 75% I 80% gave respective increases of 10 and 8 per cent in above parameter over V 0 100%NPK FYM 12.6t I AR / GRD. Further, increases in above parameter under V 12 P 100% I 40% and V 12 P 75% I 40% were to the tune of 4 and 3 per cent, respectively than GRD (Fig. 4.41). The treatments V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80%, gave higher i.e. 8, 11 and 8 per cent root weight density,

179 Root weight density (g m -3 ) Root weight density (g m -3 ) 159 1,50 1,00 1,11 0,84 0,91 0,96 1,01 1,14 1,15 1,03 1,08 1,13 1,12 1,20 1,22 0,67 0,50 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of pea during ,50 1,00 1,12 0,92 1,02 1,09 1,08 1,16 1,20 0,96 1,06 1,12 1,11 1,18 1,22 0,75 0,50 0, Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root weight density (g m -3 ) of pea during Treatment detail appears on page 32

180 160 respectively than their counterparts involving same P and irrigation levels without VAM inoculation i.e. V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%. Similarly, respective increases of 20, 25 and 20 per cent in respect of above parameter were found in case of V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40% than their non-vam counterparts involving same levels of P and irrigation regimes i.e. V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. Irrespective of VAM and irrigation levels, an increase in root weight density was observed with increasing P levels from 50 to 100 per cent of soil test based recommended P dose. However, treatments V 12 P 100% I 80% and V 12 P 75% I 80% and V 12 P 100% I 40% and V 12 P 75% I 40% gave almost similar values of above parameter. The values of root weight density given by V 12 P 100% I 80%, V 12 P 75% I 80% and V 12 P 50% I 80% treatments were 6, 5 and 11 per cent higher, respectively than treatments V 12 P 100% I 40%, V 12 P 75% I 40% and V 12 P 50% I 40%. Similarly, the magnitude of increase was 18, 19 and 23 per cent in case of V 0 P 100% I 80%, V 0 P 75% I 80% and V 0 P 50% I 80%, respectively over V 0 P 100% I 40%, V 0 P 75% I 40% and V 0 P 50% I 40%. During , data with respect to root weight density gave the same trend as that obtained during i.e. previous year (Fig. 4.42). It can be summed up that VAM inoculation enhanced pea root weight density by 15 per cent at varying P and irrigation levels. Further, treatments involving irrigation at 40 per cent of AWC gave 19 per cent higher root weight density than irrigation at 80 per cent of AWC. Above trends are attributable to same reasoning as given under above root parameters. Present results are in agreement with findings of Kothari et al. (1990), who conducted a pot experiment with maize involving a low available P soil and reported 35 per cent increase in root weight density under combined use of VAM and P than absolute control. v. Root colonization with VAM The data on root colonization with VAM in pea are depicted in Fig and In general, treatments involving application of VAM coupled with P at either irrigation regime gave higher percentage of root colonization with VAM as compared to those without VAM inoculation. The inoculation with VAM along with fertilizer P improved

181 Root colonization with VAM (%) Root colonization with VAM (%) T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root colonization with VAM (%) of pea during T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 Treatment Fig Effect of integrated application of VAM, phosphorus and irrigation on root colonization with VAM (%) of pea during Treatment detail appears on page 32

182 162 Fungal hyphae Plate 4.4. Root colonization with VAM (%) in pea under integrated application of VAM, P and irrigation during