Physiological responses of wheat cultivars to anti-transpiration compounds and drought stress ameliorators under water-deficient conditions

Anti-transpiration compounds are essential for mitigating the impact of water scarcity by reducing plant water uptake and enhancing water use efficiency. To evaluate the effects of these compounds on the physiological traits of wheat cultivars under water deficit conditions, 2 field trials were conducted during the 2019 and 2020 cultivation periods. The trails involved three irrigation levels: I1 (100 mm evaporation from Class-A pan), I2 (130 mm evaporation from Class-A pan) and I3 (160 mm evaporation from Class-A pan), which were applied to the main plots. Two bread wheat genotypes, G1 (Hydari) and G2 (Zarrineh), were used in the trails. Various anti-transpiration and stress amelioration compounds were tested, including kaolin (5 %), chitosan (200 mgL?¹), calcium chloride (50 mM), sodium selenate (40 mgL?¹) and a control treatment, which were randomized in subplots. In both years, the most significant reduction in transpiration was observed with the foliar application of chitosan following irrigation after 160 mm evaporation. Catalase (CAT) activity increased in both cultivars when subjected to foliar application of calcium chloride. Additionally, the chitosan treatment exhibited the highest peroxidase activity and the lowest malondialdehyde (MDA) activity. Notably, the chitosan treatment, particularly under irrigation withholding at the I1 level, resulted in the highest grain yield, especially with the Zarrineh cultivar. The application of anti-transpiration compounds demonstrated the ability to elevate levels of antioxidant enzymes and enhance the physiological traits of wheat under stress conditions. However, it is important to note that the extent of these improvements varies based on the timing of stress application and the type of cultivar involved.