REVIEW OF LITERATURE

Transcription

1 REVIEW OF LITERATURE

2 REVIEW OF LITERATURE In modern agriculture, pesticides have become an essential component which increases the yield by reducing the disease rate. Despite the undoubted effectiveness of these pesticides in controlling plant diseases and improving crops yield, many studies have underlined their toxic effects on crop plants. Seed germination is a complex process which involves many physiological activities at metabolic levels. Any loss in vigour by pesticidal application will reduce the process of germination which reflects on considerable economic impact. The results and reports of pesticide poisoning have been reported by many researchers since past several years. In India, the first report of pesticidal poisoning was from Kerala, where over 100 people were died after consuming wheat flour contaminated with Parathion (Karunakaran, 1958). George et al., (1970) have reported the effect of fungicidal seed treatment on germination of barley seeds and noticed many morphological changes in seedlings due to injurious action of pesticidal treatment. Shive and Hugh (1976) showed that a fungicide triarimol not only prevented the gibberellins synthesis in Phaseolus vulgaris and also checked the dry weight increase over fresh weight at higher concentrations. Treatment with fungicides severely affected the germination and seedling vigour in cotton, rice and beans has been reported by Marcos and Perri (1977). Rajanna and Oblisami (1979) suggested that interactions between various constituents of effluents are responsible for the inhibition of seed germination and seedling growth. Seed germination reduced not only by individual concentration of fungicides and insecticides, when these two are applied in combination then the effect will be severe on both germination and early growth of crop plants have been reported by Karup and Kivera (1982) and Gupta et al., (1983). 18

3 Fletcher and Nath (1984) have studied several pronounced side effects in plants including the development of shorter and more compact shoot in wheat plants treated with triadimefon fungicide. Kazuo Izumi et al., (1984) have studied the effect of S-3307 in rice plants, which retarded the plant height. Swietlik and Fucik (1988) have reported that PBZ treatment (fungicide) was found to reduce the leaf size and number of leaves in citrus. The degree of toxicity of chemicals not only affects the germination; their injurious action also affects the seed vigour associated with increased abnormal seedlings and finally results in death of the seedlings. The above said facts were studied by Benjamini (1986). Fletcher and Arnold (1986) evaluated the effect of triazole treatment in cucumber which was found to increase root growth with increased levels of cytokinins. Despite the undoubted effectiveness of systemic fungicides in controlling plant diseases and improving crops yield, many studies have underlined their toxic effects on plant. They may induce a decrease in growth as well as modulate the metabolic balance. Morphological effects of azoles molecules on plants includes reduced root elongation and trichome length, increased epicuticular wax and larger chloroplasts were reported by Fletcher and Hofstra, (1988); Gao et al.,(1988). There are several investigations to suggest that use of systemic fungicides caused significant change in morphology, seedling growth and chlorophyll content in Hibiscus esculentus (Ahmed and Siddiqui, 1995). 19

4 Further, Siddiqui, et al., (1997) have reported that usage of low dosage of Methyl thiophenate (fungicide) treatment in Sesbania sesban has been found to cause an increase in fresh and dry weight, where higher dosages have been found to be deleterious. Though most of the systemic fungicides are used as seed dressing, yet there are several reports showing phytotoxicity on various plants. Similar facts were observed by Hack, 1994: Holderness, 1990; Kaspers et al., 1987). Senapathi et al., (1992) have conducted a study on the effect of endosulfan monocrotophos and quinophos on pigeon pea and they also analyzed the pesticide residue. The above parallel work has also been reported by Pareek and Kavadia (1992) and Patil and Dethe (1995). Sahoo and Das (1994) have reported the drastic reduction in carbohydrate and protein content in Carbofuran treated rice seedlings and they suggested that application of this pesticide is not beneficial to this crop. Mark. M. Stevens et al., (1999) evaluated the Fipronil seed treatments in rice, which significantly impaired the germination. Calatayud et al., (2001) studied the effects of benomyl treatment in tomato plants. In the same year Yue-Xuan Wu et al., (2002) have reported the impact of fungicides on active oxygen species and antioxidant systems in spring barley exposed to ozone, they found that both fungicide treatments significantly increased the total leaf soluble protein content. Additionally, activities of the antioxidative enzymes superoxide dismutase, catalase, glutathione reductase were increased at maximal level. Siddiqui et al., (2001) studied the effects of Methyl thiophenate (systemic fungicide) on germination, seedling growth, biomass and phenolic content of resistant and susceptible varieties of Triticum aestivum L. and found that higher concentration 20

5 of fungicide (2000ppm) treatment reduced greatly above studied parameters. Bhattacharya et al., (2001) have investigated the effect of Carbofuran, Butachlor and Carbendazim treatments on chlorophyll and carbohydrate contents of two summer rice cultivars and found that fungicide Carbendazim application at panicle emergence of rice produced a decreasing trend in carbohydrate content. Besides its direct, antibiotic action against pathogens, the effects of fungicides in plants could be dangerous, especially at higher dosages. Even recommended dosage has exhibited weak phytotoxicity. A similar result was reported by Pablo et al., (2002) in carbendazim treated tobacco plants. The effect of xenobiotics like Gaucho and Apron of different concentrations had severe effects on seed germination, seedling growth, vigour and tolerance index, chlorophyll content and biomass in sunflower morden variety were reported by Panduranga Murthy and Leelavathi (2002). The similar results were also investigated in sorghum BS7707 and the toxicity of different exposure periods of 12, 24 and 48 hours in response to Apron and Gaucho treatments by Panduranga Murthy and Leelavathi (2003A). Iqtidar et al., (2003) have studied the effect of triadimefon applied as soil drenches retarded the growth of maize seedlings and also pigment content was not increased significantly. Angela and Flecther (2004) showed that triazole fungicides are also used as stress protectants. Treatment with triazole fungicide increased the survival percentage in wheat seedlings under heat stress. Mohanty et al., (2004) reported the effect of six fungicides application on chlorophyll content of rice and they found that Duter (fentin hydroxide) decreased the chlorophyll content. Maximum increase in total chlorophyll was observed with 21

6 captafol, followed by Dithane M-45 and Hinosan. Haroun (2005) evaluated the effect of chemical and bio- insecticides on growth, pigmentation, photosynthetic activity and yield productivity in vicia faba plants and reported that chemical insecticide (malathion) caused pronounced deleterious effect on above studied parameters and even it caused decrease in growth promoter substances (IAA, GA3 and Cytokinin). On the other hand bio- insecticide appeared to cause no significant effect on above mentioned parameters. Abdul Jaleel et al., (2006) reported the increased antioxidant enzymes activities like superoxide dismutase, ascorbate peroxidase and catalase activities in response to triadimefon treatment in Catharanthus roseus. The differential effects of Hexaconazole and Paclobutrazol on biomass, electrolyte leakage, lipid peroxidation and antioxidant potential were investigated by Gopi et al., (2007) in Daucus carota and showed that there was no significant variation in chlorophyll contents between two triazole treated plants but proved to be best when compared to control plants. Both fungicide increased alpha and beta amylase enzyme activities to a significant level. Kishorekumar et al., (2007) evaluated the comparative effects of different triazole compounds on growth, photosynthetic pigments and carbohydrate metabolism of Solenostemon rotundifolius and reported that triazole compounds increased the chlorophyll contents. However, both the treatments decreased the fresh and dry weights of shoot and leaf area. The carbohydrate metabolizing enzymes alpha and beta amylase activities were reduced under triazole treatments. Catherine and Palle (2009) studied the effect of fungicides (tebuconazole and pyraclostrobin) on Soyabean growth and yield and concluded that environmental conditions and assessment of disease levels should be used as a guide for foliar fungicide application on Soyabean. 22

7 Meena Rajalekshmi et al., (2009) have evaluated the effect of triazole growth regulators on growth and pigment contents in Plectranthus sps. and found that triazole treatments increased fresh and dry weight and pigment contents. Sangeetha (2010) has studied the effect of Carbendazim on growth parameters and activities of super oxide dismutase and catalase in fenugreek and reported that only lower concentration of Carbendazim is found to be significant on growth parameters where in higher concentration inhibited the growth parameters and increased the activity of super oxide dismutase and catalase. Pablo et al., (2002) have observed the effect of treatment of Carbendazim on healthy tobacco plants and reported that higher dosage caused the strongest decrease in dry weight and all the foliar pigments, as well as all the nutrients (N, P, K, Ca and Mg) with respect to other dosages and control. Mahesh and Hosmani (2002) studied the effect of ethyl bromide on the nutrient uptake by four cultivars of rice and noticed reduction in root and shoot length and nutrient (N, P, K, Ca and Mg) uptake. Ruske et al., (2003) have studied the effect of triazole and strobilurin fungicide on Nitrogen uptake in wheat cultivars and found that all fungicide treatments have significantly increased the amount of Nitrogen. Mahesh and Hosmani (2003) have reported the drastic reduction in root and shoot length and nutrient uptake (N, P, K, Ca and Mg) in Blitox treated rice cultivars. Same authors (2004) have done experimens to know the effect of Bavistin treatments in rice plants and observed negative influence on morphological and nutritional parameters. Zsoldos (2004) has analyzed the uptake and efflux of ions in fungicide treated rice plants and reported that treatment with Kitazin fungicide effectively inhibited the Potassium uptake. Hui Min Qiu et al., (2004) have investigated the effect of pesticide stress on rice nutrient uptake and found that high dose of pesticide had reduced the uptake of Potassium and Phosphorus significantly, but at lower concentration of pesticide the uptake of Potassium and Phosphorus was promoted significantly. 23

8 Bisht, R. et al., (2007) have evaluated the effect of triazoles on net photosynthetic rate and stomatal resistance in Setaria italica plants and reported that application of triadimefon has increased the net photosynthetic rate whereas Paclobutrazol decreased the same. Olszewski (2004) observed a tendency towards a slight decrease in the rate of photosynthesis under the influence of a fungicidal agent in horse bean and pea. Further, the same author found a significant decline in the levels of photosynthesis and transpiration under the effect of foliar herbicide application. Haroun (2005) recorded a marked decrease in pigment content and photosynthetic activity of 50 and 85 days old plant of Vicia faba treated with chemical insecticide malathion. Gopi et al., (2005) have experimented to know the effect of triazoles on growth and photosynthetic characteristics and found that fungicide treatments have increased the total root length, dry weight, moisture content, intercellular CO 2 concentrations and net photosynthetic rate but decreased transpiration rate and stomatal conductance. Iqtidar et al., (1995) have recorded the effect of morpholine systemic fungicide in wheat and maize plants. They found that the length of the shoot, primary leaf, root as well as the leaf area was significantly reduced in the treated seedlings with fungicide. The chloroplast pigments in the treated seedlings of both crops were unaffected. Sabale and Misal (1993) have reported the reduction in germination and seedling growth in jowar seeds at higher concentrations of endosulfan and methyl parathion. Sandhu (1993) and Jagadish (1993) have also reported similar results in some vegetable crops and gram cultivars. Pike et al., (1993) have investigated the inhibition of germination and growth by gaucho treatment; this in turn reduced the 24

9 yield in wheat and barley crops. In the subsequent year, Kashyap et al., (1994) and Ramdass and Shivaprakasam (1994) have conducted the study in wheat and cowpea seedlings using insecticides and fungicide treatments as dry seed treatment and they recorded negative responses in germination and early growth of crop plants. Manoj kumar and Agarwal (1998) have recorded the reduction on percent germination and seedling vigour during early growth of maize in response to fungicidal treatment. Parani and Kesavan (1999) conducted an experiment with green gram and black gram using different doses of machete butachlor, under laboratory conditions revealed that the higher dose of machete has an inhibition on early seedling growth and fresh weight of seedlings. At higher dosages severe reduction in growth was recorded. Patil and Shirashyad (1989) observed the negative response in seed germination under the treatment of methyl parathion and phosphoamidon. In addition to this, activity of alpha amylase was inhibited but peroxidase was enhanced, this reveals that the breakdown of starch to readily utilizable sugar, which is essential for the growth of seedling is greatly impaired due to insecticide treatment. Zamin Shaheed Siddiqui et al., (2001) studied the effect of systemic fungicide application in two varieties of wheat. Application of fungicide caused a significant decrease in total protein and carbohydrate content. Yadava, (2001) reported the effectiveness of paclobutrazol seed treatment on yield and plant height and observed reduction in both yield and plant height in Cape gooseberry. Studies involving fungicides and insecticides have been also shown that, they react with cellular constituents producing both physiological and germination changes. Same was reported by Zutshi and Kaul (1975) and Shrisat and Kale (1979). Bal et al., (2006) have investigated the effect of anti- damping off fungicides in 25

10 combination with seedling media in cos lettuce and found that Rizolex (fungicide) and peat combination was more favourable for length and stem diameter of seedling, fresh weight and number of leaves of the plants at harvest. Single use of benolate fungicide retarded the growth and development of seedlings. Rajendran et al., (2006) evaluated the effect of a fungicide, an insecticide and a biopesticide on Tolypothrix scytonemoides and reported that, lower concentration of Bavistin supported good growth with maximum protein and pigments content. Activities of Nitrogenase and glutamine synthetase were affected in all the pesticide treatments but Nitrogenase activity was enhanced in the presence of Bavistin. Effect of different concentrations of cytozome on chlorophyll content was studied by Gupta Renu et al., (2007) and found that the concentrations of cytozyme increased the survival percentage by delaying the senescence of leaves by increasing the chlorophyll content. Seed treatments with the Gaucho 600FS (insecticide) were evaluated to determine whether differences in concentration and exposure region influence the germination and early growth of rice by Mark Stevens et al., (2007) and results show that continuous exposure to insecticide (4 days at 2000 mg AI/ L) significantly reduced normal germination. Insecticide did not show adverse effects on plant growth if applied to pre germinated rice shortly before sowing. Ozlem et al., (2007) have studied the effect of herbicide (Fusilade) on germination, mitotic frequency and alpha amylase activity of lentil seeds. The obtained result indicates that the herbicide Fusilade had the ability to cause reduction in seed germination, mitotic frequency and also alpha amylase activity with increased concentrations of herbicide. Beside these, different concentrations of insecticide (profenophos) caused inhibition of germination, seedling height and different stages of cell cycle were sensitive to chemical treatment have been investigated by Angil 26

11 Kumar et al., (2008). Jaleel et al., have studied the effect of triadimefon (fungicide) on growth and photosynthetic pigments in two varieties of Catharanthus roseus and reported that treatments have increased chlorophyll content, fresh and dry weights. Abdul Jaleel et al., (2008) observed reduced early seedling growth in terms of shoot length and leaf area but root length got increased with a concomitant enhancement in chlorophyll contents. The non enzymatic antioxidants like ascorbic acid, reduced glutathione and activities of antioxidant enzymes like superoxide dismutase, peroxidase and catalase were increased. Triazoles compounds have both fungi toxic and plant growth regulating properties. Previous works revealed the morphological and physiological changes associated with triazole treatment in various plants which includes the inhibition of plant growth, decreased intermodal elongation, increased chlorophyll levels, enlarged chloroplasts, thicker leaf tissue, increased root to shoot ratio, increased antioxidant potentials and enhancement in alkaloid production. Similar results were observed by Abdul Jaleel et al., (2008) in triazole treated potato. Vidyasagar et al., (2009) have studied the effect of endosulfan in mediating stress response in sorghum and found that, all the concentrations of endosulfan tested were proved to be inhibitory over seed germination, shoot and root length and biomass. Even chlorophyll a and total chlorophyll content decreased significantly with an increase in endosulfan treatment. Endosulfan treated seedlings showed sudden increase in amylase activity in lower concentration where as in higher concentrations, the activity was found to be decreasing. Similar results were reported by Kevin et al., (2009) in three wet land plants treated with triclosan. 27

12 Moore et al., (2010) have evaluated the effects of three insecticides and two herbicides on rice seedling germination and growth and observed negative influence on growth. Pesticides treated to seeds have tendency to penetrate into tissue of the plants. There they transformed into metabolites, which are physiologically more active than the parent compounds and finally affects the seed health and quality. Zsolods and Haurnold (1978) have looked into the effects of some selected herbicides on uptake of Potassium and growth of rice seedlings. Herbicide treatments were found to inhibit the uptake of Potassium ions and rice seedling growth. Alterations of one or several essential nutrient elements is one of the most common causes affecting chlorophyll and other photosynthetic pigments and hence carbon assimilation. Reiger and Scalabrelli (1990) reported that PBZ (Paclobutrazol) induced an inhibition of root growth, from which differences in mineral uptake may be expected. Increased activity of enzyme catalase has been recorded in organophosphorus pesticide treated vegetables viz, bean, okra, guar and onion by Shirashyad et al., (2009). Even though chemical treatments are most effective measures to control plant diseases, despite their many advantages, there are some potential hazards while using these chemicals. Synthetic fungicides have effectively controlled plant diseases for a number of years, but increasing concern over environmental effects of the currently used fungicides has highlighted the need for the development of alternative types of selective control methods of crop protection with or without reduced use of conventional fungicides (Kim et al., 2003). 28

13 Tricyclazole is one such fungicide which is widely used as a systemic fungicide to control leaf blast and neck and panicle blast in the rice crops. Tricyclazole belongs to triazole group of fungicide developed by Indofils chemical company, Dr. Annie Besant Road, Worli, Mumbai. Indofil s BAAN (Tricyclazole 75%wp). Composition Tricyclazole Technical 95%. Sodium lauryl sulphate. Reax 45 L (Sodium lignosulphonate). Hisil (Synthetic hydrated PPTD Silica). Spesh white (China clay). Regulatory status BAAN is a trade name for the systemic fungicide tricyclazole. Tricyclazole is a slightly toxic compound in EPA toxicity class II and its chemical class is triazole. It is a general fungicide used particularly for controlling blast disease of rice. Its molecular formula is C 9 H 7 N 3 S and molecular weight is about Its chemical name is 5 methyl-1,2,4-triazole [3,4-6]- benzothiazole]. Structural formula: 29