Effect of Plant Growth Regulators On Water Relations, Proximate Composition, and Ascorbate/glutathione Cycle of Late-sown Wheat Under Saline Conditions

Wheat production frequently faces challenges from saline stress (SS) and late sowing (LS) conditions in semi-arid and arid regions of South Asia due to seawater intrusion in multiple cropping systems; however, the wheat responses under combined stress conditions are still elusive. In the present study, the effects of sowing time (normal and late-sown), field conditions (non-saline and saline), and plant growth regulators (PGRs) such as hydrogen peroxide (H₂O₂; 100 µM), salicylic acid (SA; 100 mg L⁻¹), thiourea (TU; 1000 mg L⁻¹), and water (H₂O) spray were assessed at three different stages of wheat. The aim was to mitigate the adverse effects of late sowing (LS) and saline stress (SS; 110 mM) and their combinations on water relations, floret fertility, and grain quality. Data revealed that floret fertility, chlorophyll stability index, stress tolerance index, grain length, grain width, ash, crude fat, crude fiber and water relations decreased while electrolyte leakage and superoxide anion and ascorbate/glutathione increased under all stress conditions. However, the application of PGRs increased the antioxidant activity and reversed the damage caused by combined stress. The trend of improvement was TU > SA > H₂O₂ > H₂O > control. The stress severity trend was SS + LS > SS > LS, as confirmed by the higher chlorophyll stability index and stress tolerance index.