Inducing Salt Tolerance in Wheat by Exogenously Applied Ascorbic Acid through Different Modes

In order to assess whether exogenous application of ascorbic acid (AsA) through different ways could alleviate the adverse effects of salt- induced adverse effects on two wheat cultivars differing in salinity tolerance, plants of a salt tolerant ('S-24') and a moderately salt sensitive ('MH-97') cultivar were grown at 0 or 120 mM sodium chloride (NaCl). Ascorbic acid (100 mg L-1) was applied through the rooting medium, or as seed soaking or as foliar spray to non-stressed and salt stressed plants of wheat. Salt stress-induced reduction in growth was ameliorated by exogenous application of ascorbic acid through different ways. However, root applied AsA caused more growth enhancement under saline conditions. Leaf ascorbic acid, catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities were also maximal in salt stressed plants of both cultivars treated with AsA through the rooting medium. Furthermore, leaf ascorbic acid, CAT, POD, and SODactivitieswere higher in salt stressed plants of 'S-24' than those of 'MH-97'. Root applied AsA caused more enhancements in photosynthetic rate. Root applied AsA caused more reduction in leaf sodium (Na+) compared with AsA applied as a seed soaking or foliar spray. Overall, AsA- induced growth improvement in these two wheat cultivars under saline conditions was cultivar specific and seemed to be associated with higher endogenous AsA, which triggered the antioxidant system and enhanced photosynthetic capacity.