Effect of mineral nitrogen on shoot biomass and concentrations of some elements in alfalfa leaves under salinity conditions

Transcription

1 International Research Journal of Applied and Basic Sciences. Vol., 3 (8), , 2012 Available online at www. irjabs.com ISSN X 2012 Effect of mineral nitrogen on shoot biomass and concentrations of some elements in alfalfa leaves under salinity conditions Farideh Abbasi-Shahmersi 1*, Ali Ebadi 2 1- MSc student of Agronomy, department of Agriculture, University of Mohaghegh Ardabili, Ardabil, Iran. 2- Department of Agriculture, University of Mohaghegh Ardabili, Ardabil, Iran *Corresponding Author f.shahmersi@yahoo.com Abstract Effect of nitrogen on yield and accumulation of some ions in alfalfa were studied at saline condition. A factorial experiment was conducted based on completely randomized design with three replications in the University of Mohaghegh Ardabili, Ardabil, Iran, at Alfalfa seeds (Hamedani cultivar) inoculated with the Rhizobium bacteria and grown in 5 kg pots. Nitrogen fertilizer of 0, 30, 60 and 90 kg ha -1 was applied as urea at 4 to 6 leaf stage. After the establishment of seedlings, salinity was imposed at zero, 100 and 200 mm as NaCl. The amounts of sodium, potassium and calcium measured by flame photometer. Yield and Fe content also were measured. Results showed that salinity increased the amount of sodium, calcium and Fe ions significantly but it had no effect on potassium concentration. Sodium to potassium ratio and shoot biomass also decreased significantly by salinity. Although, nitrogen fertilizer had no significantly effect on the amount of absorbed ions but it increased alfalfa yield. Keywords: Alfalfa, Nitrogen, salinity, yield. Introduction Salinity stress is one of the important and common abiotic stresses that reduces crop production and productivity of arable lands in arid and semi-arid regions (Bybordi et al, 2010). It is estimated that over than 300 million hectares of all cultivated land and nearly half of irrigated land is salt-affected (Rahmani and Majidi, 2002). On an average, 20% of the world s cultivated area and nearly half of the world s irrigated lands are affected by salinity, but this value increases to more than 30% in countries such as Egypt, Iran and Argentina (Zhu, 2001). Nitrogen is the most important nutrient that its uptake Is limited over other elements under saline conditions. Salinity reduces the activity of nitrogenase and directly limits nitrogen uptake by reducing the root cells membrane permeablity (Khan et al., 1995). Sodium chloride accumulation in shoot organs of plants considered as a mechanism for osmo regulation. Such ions accumulate in vacuoles of resistant plants and osmotic balance between vacuoles and cytosol and apoplast obtained by accumulation of compatible solutes such as proline. But in susceptible plants sodium and chloride accumulation in cytosol is toxic and their accumulation in apoplast cause reduction in enzymes activity and cell water exertion and water deficit condition (Marschner, 1995 and Munns, 1993). Sodium prevents the absorption of other elements as: 1 - replacement of sodium in the cell membrane transporters such as potassium selective channels 2 - reduction in root growth at high concentrations of sodium (Tester and Davenport, 2003). Yeo and Flowers (1983) stated that increasing sodium accumulation may change cell osmotic potential witch cause plasmolysis and losses of selective absorption of root cells. According to Munns (1993) plant growth in these conditions cause to accumulate higher amounts of chlorine and sodium ions in the shoot that will lead to earlier leaf senescence. Increasing sodium ion in the root zone reduce potassium uptake (Benlloch et al. 1994)

2 and lower potassium to sodium ratio in various physiological and biochemical activities of the plant. Suhayda et al. (1992) declared that there is a strong relationship between the ratio of potassium to sodium and salt tolerance in barley. Abdolzadeh et al. (2006) reported that salinity affects the sodium, potassium and chloride concentration in roots and shoot parts of rapeseed. Esmaili et al. (2008) studied the interaction of salinity and nitrogen on sorghum growth and composition and stated that sodium and calcium content in plant tissues significantly increases by increasing salinity stress, whereas the concentration of potassium and uptake of calcium, potassium and magnesium ions decreases. They stated that such an increase in calcium and magnesium content is as a result of higher calcium and magnesium ions concentrations in saline water. Leigh and Wyn Jones (1984) reported that a decrease in potassium ion concentration due to salinity inhibits the growth of the leaves through reduction in osmoregulation capacity or impact on the metabolic activities such as protein synthesis. Research results also showed that micronutrient concentrations in plant shoots increased with increasing salinity. The high concentration of salt, increased iron and zinc concentrations in roots and decreases Mn concentration (Mass et al. 1972). Ya, ling (2001) reported that increasing the salinity of nutrient solution in tomato root significantly increase uptake of macro and micro nutrients. Relationship between salinity and fertilizer has economic importance and many studies have been done to evaluate the nitrogen and other nutrients absorption by plants under saline conditions (Basal et al, 2006). In this study the effect of nitrogen was investigated on the absorption of some elements in the shoot, alfalfa yield and water use efficiency in saline conditions. Materials and Methods This study was conducted in a completely randomized design based on factorial experiment with three replications in greenhouse condition in Alfalfa seeds were sterilized and inoculated with the rhizobium and planted in 5 kg pots in soil. After the plants grow and to 4-6 leaf stage nitrogen fertilizer was applied based on zero, 30, 60 and 90 kg ha -1. Salinity imposed at three levels of zero 100 and 200 mm 7 days after nitrogen application. To determine the elements one gram of shoot dry matter ashes at 500 C. Then samples heated by adding 10 ml of 2N hydrochloric acid to boiling point. Then the samples filtrated and reached to 100 ml with distilled water. Concentrations of elements were measured by Flame spectrometer. Standards of 0.5, 1.25, 2.5, 5, 7.5 and 10 ppm was used for obtaining standard curve (Burgan, 2006). Fe contents were determined by spectrophotometer (Harris, 2003). Data were analyzed by an analysis of variance using SAS software to test the significance of the main effect. Means were compared using LSD tests. Results and discussion The amount of sodium and calcium accumulation in shoots was affected by salinity ( = %1), while nitrogen fertilizer did not affect the accumulation of these elements. Potassium was not affected by nitrogen fertilizer none of the treatments had significant effect on potassium content. Naidoo and Naidoo (2001), and Esmaili et al. (2008) also reported that the ions concentration was significantly affected by salinity and nitrogen, but there was no significantly interaction between salinity and nitrogen application. Sodium was increased with increasing salinity in alfalfa leaves (Fig 1). Accumulation of Na in alfalfa at 100 mm Salinity was mg in leaves and at 200 mm salinity mgg -1 shoot dry weight. The highest ions accumulation belonged to 200 mm salinity level. Abdul-Zadeh et al (2008), Esmaili et al. (2008), Naidoo and Naidoo (2001) and Bybordi et al. (2010) have also reported that salinity increases the amount of sodium accumulation. Accumulation of Na leads to changes in osmotic potential of cells that can cause plasmolysis and lower the potential of root cells in selective absorption (Yeo and Flowres, 1983). Sodium prevents the potassium absorption. Because the nitrate transports from roots to leaves by xylem, and potassium stimulate this process, When sodium and chlorine ions enters to the vascular system in large quantities, sodium ions can be prevented the absorption of potassium ions, with reduction the amount of potassium, the transmission of nitrate also is less. So instead of nitrate, chlorine anion transfers to the leaves and it accumulate there. (Siliberabush and Ben- Asher, 1987). With increasing salinity, calcium content also increased significantly (Fig 1). High salinity increases cytosicolic calcium which translocats via apoplast and intracellular parts. The Increasing calcium enhances the directing of signal toward adaptation to salinity stress. (Parida et al., 2002). Esmaili and colleagues (2008), Bybordi (2011) have also pointed to the results of their research. Adverse effects of calcium ions will neutralize harmful (Bilski et al,

3 1988). Sodium and calcium may reduce the competition with its absorption or uptake of potassium (Cramer et al, 1989) will reduce the damage of salt stress. In this study, potassium were not affected by salinity. Makus (2003) has reported similar results. But the ratio significantly decreased with increasing salinity (Fig 2). Ratio of potassium/ sodium is an important indicator of salt sensitivity. Decrease in potassium/sodium ratio in saline conditions by Jackson & Volk (1997) and Bybordi et al (2011) has also been reported. With increasing salinity level amount of Fe also increased significantly. The minimum concentration of Fe obtained in control (non saline) and the highest concentration obtained in 200 mm NaCl. In fact Amount of Fe was decreased 37.16% and 85.65% respectively with increasing salinity up to 100 and 200 mm NaCl (Fig.3). Other researchers have reported a significant increase in Fe concentration in some plants under the influence of Martinz et al., 1987). This increase may be due to applying these elements in osmotic regulation of plants in response to salinity (Zahedifar, 2010). Shoot biomass of alfalfa affected by salinity and nitrogen schedules (=1%). The highest amount of dry matter related to 90 kgha -1 of Nitrogen and the lowest biomass obtained from control of (Fig 4). With increasing salinity also the amount of shoot biomass significantly decreased (Fig 5). Other researchers also suggested that salinity reduced biomass production in alfalfa. (Khan et al., 1994; Seraj & Drevon 1998). Golzar (2003) and Naseer (2001) reported the effect of salinity on roots and shoot dry weight. Salinity has both osmotic and also specific ion effects on plant growth (DionisioSese & Tobita, 2000). Reduction in plant growth as a result of salt stress has also been reported in several plant species (Ashraf and McNeilly, 1990 Salinity in soils restricts water availability to plants in a similar manner to water stress, which causes reductions in growth rate and even in production (Munns, 2002). The reduction in shoot biomass by the plant may be due to the chlorosis and necrosis of the leaves that reduce the photosynthetically active area (De Herralde et al., 1998). Figure 1. Effect of salinity on sodium and calcium content Figure 2. Effect of salinity on Potassium/sodium Figure 3. Effect of salinity on leaf Fe content

4 Figure 4.Effect of nitrogen on alfalfa shoot biomass Figure 5.Effect of salinity on alfalfa shoot biomass Conclusion Results showed that salinity and nitrogen affects some traits. Enhancing the salinity significantly increases sodium, calcium and iron concentration, whereas K/Na ratio is decreased. Salinity also reduces the amount of biomass. Results also indicate that nitrogen didn t significantly effect on the amount of this elements while with increasing the amount of nitrogen in alfalfa it significantly increases shoot biomass. References Abdolzade A, Malekjani Z, Galeshi S, Yaghmaei F, Combined effect of salinity on growth and nitrogen nutrition of rapeseed. JAST. 13: Ashraf M, Mcneilly T, Improvement of salt tolerance in maize by selection and breeding. Plant Breeding. 104: Ashraf M, O leary JM, Responses of some newly developed salt tolerant genotypes of spring wheat to salt stress. 2. Water relations and photosynthetic capacity. Acta botanica. 46: Basal H, Hemphill JK, Smith CW, Shoot and root characteristics of converted race stocks accesions of upland cotton (Gossypium hirsutum L.) grown under salt stress conditions. J Plant Pathol.1(1): Benlloch M, Ojeda MA, Ramos J, Rodriguesnanavarro A, Salt sensitivity and llow discrimiation between potassiumand sodium in plants. Plant and soil. 166: Bilski JJ, Nelsin DC, Colon RL, The response of four potato cultivars to chloride salinity, sulphat salinity and calcum in pot experiment. Potato Journal. 65, Borgan JC, Flame Photometric determination of calcium in plants. J Sci food and Agric. 11(8): Bybordi A, Tabatabaei SJ, Ahmadev A, Effect of salinity on fatty acid composition of Canola (Brassica napus L). J Food and Agric Environ. 8(1): Bybordi A, Tabatabai S, Ahmadaf A, Effect of NaCl salinity induced physiological characteristics, quantity and quality of winter oilseed rape cultivars. Journal of Water and Soil (Science, Industry and Agriculture). 24: Cramer GR, Epstein E, Lauchi A, Na-Ca interactions in barley seedling: relationship to ion transport and growth. Plant Cell Environmental. 12: De Herralde F, Biel C, Save R, Morales MA, Torrecillas A, Alarcon JJ, SanchezBlanco MJ, water relations in Argyranthemum coronopifolium plants. Plant Sci. 139(1): DionisioSese ML, Tobita S, Antioxidant responses of rice. Seedlings to salinity stress. Plant Sci. 135, 1-9. Esmaili E, Kapourchal SA, Malakouti MJ, Homaee M, Interactive effect of salinity and two nitrogen fertilizers on growth and composition of sorghum. Plant Soil Environ. 54 (12): Golzar S, Khan MA, Ungar IA, Salt tolerance of a coastal salt marsh grass. Comunication in soil science and Plant Analysis. 34: !!" #$%&' ( )*-261, , 453, ,

5 Jackson WA, Volk RJ,1997. Role of potassium in photosynthesis and respiration. In: Madison, W.S. (Ed), The role of potassium in agriculture. American. Soc. Agronomy Khan MG, Silberbush M, Lips SH, Physiological studies on salinity and nitrogen interaction in alfalfa plants: III. Nitrate reductase activity. J Plant Nutr. 18(11): Leigh RA, Wyn Jones RG, A hypothesis relating critical potassium concentrations for growth to the distribution and functions of this ion in the plant cell. New Phytol. 97:1-13. Makus DJ, Salinity and Nitrogen Level Affect Agronomic Performance, Leaf Color and Leaf Mineral Nutrients of Vegetable Amaranth. Subtropi. Plant Sci. 55: 1-6. Marschner H, Mineral nutrition of higher plants, Academic Press. Martines V, Nunez JM, Orriz I, Cerda A, Changes in amino acid and organic acid composition in tomato and cucumber plants in relation to salinity and nitrogen nutrition. J plant nutr. 17 (8): Mass EV, Haffman GY, Crop salt tolerance current assessment. J.irrig, Drain. Div. ASCE. 103: Mass. E.V., Ogata, G, Garber, MJ, Influence of salinity on Fe, Mn, and Zn uptake by plants. Agron J. 64: Munns R, Physiological process limiting plant growth in saline soil: some dogmass and hypotheses. Plant Cell and Environ. 16: Munns R, Comparative Physiology of Salt and Water Stress. Plant Cell and Environ. 25: Naidoo G, Naidoo Y, Effects of salinity and nitrogen on growth, ion relations and proline accumulation in Triglochin bulbosa. Wetlands Ecol. Management. 9: Naseer S, Response of barley (Hordeum vulgar L.) at various growth stage to salt stress. J Biol. Sci. 1: Parida AK, Das AB, Das P, NaCl stress causes changes in photosynthetic pigments, proteins and other metabolic components in the leaves of a true mangrove, Bruguiera parviflora, in hydroponic cultures. J Plant Biol. 45: Rahmani M, Majidi A, Effect of NaCl salinity stress on wheat enzymes. Seed and Plant J. 2: Serraj R, Drevon J, Effects of salinity and nitrogen source on growth and nitrogen fixation in alfalfa. J plant nutr. 21(9): Siliberabush M, ben- Asher J, The effect of salinity on parameters of potassium and nitrate uptake of cotton commun. In soil Science plant Anal. 18(1): Suhayda CG, Redman RE, Harvey BL, Cipywnyk AL, Comparative response of cultivated and wild barley species to salinity stress and calcium supply. Crop Sci. 32: Tester M, Davenport R, Na + tolerance and Na + transport in higher plants. Annual Botany. 91: Ya, Ling L, Stanghellini C, Challa H, Effect of electrical conductivity and transpiration on production of greenhouse tomato (Lycopersicon esculentum L.). Scientia Hort. 88: Yeo, AR, Flowers TJ, Varietal differences in the toxicity of sodium ions in rice leaves. Plant Physiol. 56: Zahedi far M, Ronagi A, Mosavi SA, Safarzade- Shirazi S Effects of salinity and nitrogen on nutrient distribution, citric acid and vitamin C in tomatoes. Journal of Science and Technology of Greenhouse Culture. 1(3): Zhu JK, Plant salt tolerance. Trends in Plant Sci. 6: