Exogenous Application of Salicylic Acid through Rooting Medium Modulates Ion Accumulation and Antioxidant Activity in Spring Wheat under Salt Stress

An experiment was conducted to assess whether exogenous application of salicylic acid through hydroponic culture could alter the ion concentrations and activate some antioxidative enzymes (superoxide dismutase, catalase & peroxidase) of a salt tolerant line (S-24) and a moderately salt sensitive cultivar (MH-97) of wheat. Seeds of cultivar were germinated in 0 or 150 mM NaCl in Hoagland's nutrient solution containing different levels of salicylic acid (SA) (0, 0.25, 0.50, 0.75 & 1.00 mM) for 7 d. Seven-days old wheat seedlings were transferred to hydroponics and grown at 0, or 150 mM NaCl for further 30 days. After 30 d, S-24 performed better than MH-97 under saline conditions with respect to ion accumulation and antioxidant activities. Exogenous application of SA promoted the activities of antioxidative enzymes and proline accumulation and ameliorated the adverse effects of salinity on growth of S-24, whereas there was no improvement in the salt sensitive cultivar MH-97. Of the varying SA levels used, the most effective levels for promoting antioxidant activity and ion accumulation were 0.25 and 0.75 mM under normal and saline conditions, respectively. The improvement in salinity tolerance due to SA application was associated with enhanced Na+, Ca2+ and Cl- uptake and antioxidative enzymes activities.