Exploring the potential of foliar phytohormone application for mitigating water deficit in wheat cropping systems under arid soils.

In arid regions, water scarcity prompts the overuse of chemical growth regulators, posing ecological and health risks. This study investigates foliar application of microbial phytohormones as a sustainable alternative to mitigate the water deficit's negative impact on wheat growth and enhance crop productivity. Field experiments over two seasons evaluated the impact of microbial phytohormones microbial gibberellic acid (MGA3) and microbial ascorbic acid (MASA) on wheat yield and water productivity under three deficit irrigation levels: 100%, 80%, and 60% of crop evapotranspiration (ETc). The treatments significantly influenced growth, grain yield, and associated characteristics. Deficit irrigation adversely affected wheat growth and yield. However, MGA3 and MASA foliar treatments significantly improved plant height, flag leaf area and yield components under water stress. The highest grain yield (4.27 t ha ⁻ ¹) was achieved with 100% ETc + MGA3, while the highest irrigation water productivity (IWP, 1.16 kg m ⁻ ³) was recorded with 60% ETc + MGA3. Redundancy analysis confirmed MGA3's superiority over MASA and control (CK) in enhancing grain yield and crop water productivity (CWP), which were strongly correlated with biological yield and seed index. This study concludes that microbial phytohormones, particularly MGA3, are effective agronomic tools for sustaining wheat productivity in water-scarce arid environments.