Effects of exogenous calcium on photosynthetic characteristics and carbohydrate metabolism in leaves of cucumber(Cucumis sativus L.)seedlings under NaCl stress
A hydroponic experiment was conducted to investigate the effects of exogenous calcium on contents of photosynthetic pigments,photosynthetic gas exchange,chlorophyll fluorescence parameters and carbohydrate metabolism in leaves of cucumber,witha salt-sensitive cucumber(Cucumis sativus L.) cultivar‘ Jinchun 2’ under salt stress.The results showed that 75 mmol· L-1 NaCl inhibited the synthesis of photosynthetic pigments in leaves of cucumber seedlings,and damaged the structure of PS Ⅱ and the net photosynthesis was reduced by 46.9％.Furthermore,salt stress induced an increase in contents of sucrose,starch and total soluble sugar and the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in cucumber leaves.However,the amylase activity in leaves of cucumber was reduced by salt stress.Compared with cucumber seedling treated with salt stress alone,the net photosynthesis of cucumber seedlings increased by 18.5％ due to exogenous calcium application,and calcium significantly alleviated the decreased photosynthetic pigments contents,photosynthesis activities and the increased carbohydrates contents as well as SS and SPS activities in salt-stressed cucumber seedlings.In contrast,exogenous calcium increased amylase activity in cucumber leaves under salt stress.These results suggested that exogenous calcium could alleviate the damage on photosynthesis induced by salt stress and enhanced salt tolerance of cucumber seedlings by increasing photosynthetic pigments,regulating the plant stomatal opening and key enzymes activities related to carbohydrate accumulation,maintaining the PS Ⅱ activity and reducing the negative feedback inhibition to photosynthesis caused by carbohydrate accumulation in leaves under stress condition.
国家科技期刊平台
NSTL
万方数据
维普
