Enhancement of Antioxidant Defense System Induced by Hormonal Priming in Wheat

Use of plant hormones as seed priming agents is known to improve the field performance especially under stressful conditions like salinity. A pot experiment was conducted to study the effects of seed priming of two wheat (Triticum aestivum L.) cultivars Auqab-2000 (salt tolerant) and MH-97 (salt sensitive) under saline (15 dS m(-1)) and non-saline (2.75 dS m(-1)) conditions. For priming seeds were soaked in aerated water (hydropriming), and solutions of kinetin (Kin; 25 mg L(-1)), or salicylic acid (SA; 50 mg L(-1)) for 12 h. All the priming treatments significantly reduced the adverse effects of salinity in terms of improving final emergence, growth and grain yield of both cultivars. Seed priming with SA and Kin improved salt tolerance in both wheat cultivars by the activation of antioxidants, i.e. superoxide dismutase (SOD) and catalase (CAT) to counterbalance the oxidative damage. Albeit, Na(+) and Cl(-) contents increased due to salinity, all priming strategies lowered the accumulation of Na(+) and enhanced the accumulation of K(+) in leaves of both cultivars. The results suggest that priming with SA followed by kinetin successfully improved fitness of wheat plants exposed to salt stress.