SALICYLIC ACID ALLEVIATES SALINITY STRESS THROUGH THE MODULATION OF BIOCHEMICAL ATTRIBUTES AND SOME KEY ANTIOXIDANTS IN WHEAT SEEDLINGS

A study was conducted to evaluate the role of salicylic acid (SA; 0, 0.5 and 0.75 mM) on the growth and activity of antioxidant enzymes and biochemical attributes in wheat (Triticum aestivum L.cv. Sods 1) under salinity stress. Salinity exposure (0, 25, 75 and 125 mM NaCl) reduced growth of wheat significantly by reducing the fresh and dry weight of shoot and root, leaf development and inducing necrosis on old leaves. Lipid peroxidation and production of hydrogen peroxide (H2O2) increased by 3.37 fold and 2.54 fold, respectively, while membrane stability declined with 125 mM NaCl concentration which were however, ameliorated by the application of SA. Under normal conditions, application of SA (0.5 mM) improved growth significantly compared to the untreated controls. Salinity (125 mM) stress enhanced the accumulation of proline (4.63 fold), carbohydrates (39.61%), free amino acids (9.44) and protein content (7.91%) which were further stimulated by application of SA leading to better stress adaptation. Application of SA to salinity stressed upregulated the activity of antioxidant enzymes like SOD, CAT and APX by 1.76 fold, 2.25 fold and 2.22 fold, respectively leading to better elimination of reactive oxygen species and protection against oxidative stress. Moreover, excess uptake of Na in salinity stressed plants reduced the uptake of K+ and initiated leaf necrosis. However, application of SA mitigated these negative effects to considerable extent. In conclusion, salinity stress adversely affected the growth and development of wheat plants. However, supplementation of proper dosage of SA mitigated these negative effects of salinity through the modulation of the levels of osmolytes, activities of antioxidant enzymes and uptake of essential elements.