Integrated Application of Hydrogen Sulphide and Gibberellic Acid Enhances Salinity Stress Tolerance in Wheat (<i>Triticum aestivum</i> L.)

This study investigated the role of exogenously applied hydrogen sulfide (HS; 50 μM) and gibberellic acid (GA; 200 mg L1) in alleviating salt stress (100 mM NaCl) in wheat. The applied HS and GA significantly improved plant height, biomass, chlorophyll and carotenoids, with the highest enhancement under their combined application. Salt stress markedly increased hydrogen peroxide, methylglyoxal, lipid peroxidation, lipoxygenase and NADPH oxidase, whereas HS and GA treatment reduced these effects. Both HS and GA further enhanced proline and sugar accumulation, increased γ -glutamyl kinase activity, and decreased proline oxidase. Activities of antioxidant enzymes and the glyoxalase cycle, as well as the levels of GSH, cysteine, ascorbic acid, tocopherol and methionine, were elevated by HS and GA. Salinity raised endogenous NO and HS levels, while their external application reduced these levels. HS and GA also decreased Na+ and increased K+ and Ca2+. Overall, treatments of HS and GA mitigated salinity stress by enhancing tolerance mechanisms, redox homeostasis and nutrient balance.