Effect of cytokinin and brassinosteroid treatments on some biochemical and physiological of wheat cultivars under drought stress in generative phase

In order to effect study and comparison of exogenous application of individual and combined hormonal treatments of kinetin and 24-epibrassinolide on some biochemical traits and weight of thousand grains in three wheat cultivars with different tolerance to water deficit period including Pishtaz (tolerant), Sabalan (semi-tolerant) and Gaspard (susceptible)  under drought stress during booting origin, the pot experiment as factorial design with four replications was conducted in Yazd university in 2015. Therefore, treatments included factors of cultivar in three levels, drought stress in two levels (field capacity of 100% or control and 50% or drought stress)    and hormones applications in four levels of non-hormone, kinetin (100 µm), 24-epibrassinolide (1 µm) and their interaction. The flag leaves were applied for analysis. Drought exposure resulted to the most reduction of chlorophyll a, b, a+b, a/b ratio, carotenoid, and weight of thousand grains in susceptible cultivar (Gaspard). The highest significant increment of abscisic acid, soluble sugar, proline level and soluble sugar/starch ratio were observed in tolerant cultivar. 24-epibrassinolide resulted to the most significant increasing of abscisic acid and soluble sugar/starch ratio and kinetin and 24-epibrassinolide combination caused the highest increment of pigment, proline and protein content and also weight of thousand grains during drought exposure in tolerant cultivar (Pishtaz), especially. Results of this research showed that influence of hormonal treatment on chemical treatment was more than their effect on weight of thousand grains. Kinetin and 24-epibrassinolide combination resulted to more influence than individual treatment of hormones on chemical traits and weight of thousand grains. Pishtaz cultivar (tolerant) was benefited from hormonal treatments in related to tolerance of water deficit.