Gibberellic acid mediated induction of salt tolerance in wheat plants: Growth, ionic partitioning, photosynthesis, yield and hormonal homeostasis

In order to elucidate the GA(3)-priming-induced physiochemical changes responsible for induction of salt tolerance in wheat, the primed and non-primed seeds of two spring wheat (Triticum aestivum L) cultivars, namely, MH-97 (salt intolerant) and Inglab-91 (salt tolerant) were sown in a field treated with 15 dS m(-1) NaCl salinity. Although all the three concentrations (100, 150 and 200 mg L-1) of GA(3) were effective in improving grain yield in both cultivars, the effect of 150 mg L-1 GA(3) was much pronounced particularly in the salt intolerant cultivar when under salt stress. Seed priming with GA(3) altered the pattern of accumulation of different ions between shoots and roots in the adult plants of wheat under saline conditions. Treatment with GA(3) (150 mg L-1) decreased Na+ concentrations both in the shoots and roots and increased Ca2+ and K+ concentrations in the roots of both wheat cultivars. GA(3)-priming did not show consistent effect on gaseous exchange characteristics and the concentrations of auxins in the salt stressed plants of both wheat cultivars. However, all concentrations of GA(3) reduced leaf free ABA levels in the salt intolerant, while reverse was true in the salt tolerant cultivar under saline conditions. Priming with GA(3) (150 mg L-1) was very effective in enhancing salicylic acid (SA) concentration in both wheat cultivars when under salt stress. Treatment with GA(3) (100-150 mg L-1) lowered leaf free putrescine (Put) and spermidine (Spd) concentrations in the plants of both wheat cultivars. The decrease in polyamines (Put and Spd) and ABA concentrations in the salt stressed plants of the salt intolerant cultivar treated with GA(3) suggested that these plants might have faced less stress compared with control. Thus, physiologically, GA(3)-priming-induced increase in grain yield was attributed to the GA(3)-priming-induced modulation of ions uptake and partitioning (within shoots and roots) and hormones homeostasis under saline conditions. (C) 2010 Elsevier B.V. All rights reserved.