Effects of Exogenous EBR on Photosynthetic Physiology of Cowpea Under Waterlogging, Drought and Salt Stress

Taking ‘Ejiangdou 7’and ‘Jiangda Zijiang 1 Hao’two long cowpea varieties as test materials, the field cowpea plants were subjected to single salt stress, salt and drought dual stress, and salt and waterlogging dual stress respectively, the method of spraying brassinolide（EBR） was used, photosynthetic indicators（net photosynthetic rate, intercellular CO₂ concentration, stomatal conductance and transpiration rate）,antioxidant enzymes indicators and malondialdehyde content indicators were measured and detected, the effects of brassinolide on the physiology and biochemistry of cowpea seedlings under external stress were studied, in order to provide reference for the application of exogenous brassinolide to alleviate cowpea strress.The results showed that under the conditions of waterlogging, drought and salt stress, the stomatal conductance（Gs）,transpiration rate（Tr） and intercellular CO₂ concentration（Ci） of cowpea leaves decreased, resulting in the decrease of stomatal opening and closing degree, and the reduction of photosynthesis.Insufficient raw material CO₂ reduced the net light rate（Pn）,exogenous EBR improved the photosynthesis of cowpea leaves under waterlogging, drought and salt stress, and exogenous EBR treatment increased the net photosynthetic rate of cowpea, reduced the concentration of intercellular CO₂,stomatal conductivity and transpiration rate.Under waterlogging, drought and salt stress conditions, the activities of SOD,POD,CAT,APX and MDA contet in cowpea all increased.