Influence of 24-epibrassinolide on some physiological characteristics and the yield of Coriandrum sativum L. under drought stress

This experiment was conducted in order to investigate effects of drought stress and 24-epibrassinolide effects on some physiological and antioxidant enzyme activity of medicinal Coriandrum sativum L. as split plot based on randomized complete block design with three replications in Jiroft, south of Kerman. The treatments consisted of three levels of irrigation at -2 bar (moderate drought), irrigation at -3.5 bar(mediate drought) of matric potential, mediate drought and -4.5 bar of matric potential (severe drought) as the main factor and three concentrations of 24-epibrassinolide as foliar spraying (0, 0.5 and 1 µM) as the sub factor. Results showed that according to significant effects of drought levels, the most values of RWC, total chlorophyll, carotenoide content and soluble protein and also, the most values of ion leakage percentage and reduced sugars were obtained in plants treated under moderate drought level (-2 bar). The effect of foliar spraying with 24-epibrassinolide was significant on ion leakage percentage and soluble proteins. The least values of ion leakage percent and the most value of soluble protein were obtaind in plants treated with 1µM of brassinolide. The mutual effects between drought levels and spraying with brassinolide were significant on vegetative yield of coriander. The most average of vegetative yield was obtained in plants under moderate drought at all three concentrations of brassinolide that they had not significant difference with yield average of plants treated by mediate level of drought and 0.5 µM of brassinolide.