Effects of Exogenous Nitric Oxide on Growth and Antioxidant System in Cucumber Seedlings under Ca(NO_3)_2 Stress

The study was conducted in nutrient solution to investigate the effects of exogenous nitric oxide(NO) on growth of cucumber seedlings,antioxidant enzyme system under Ca(NO3)2 stress.The results showed that the growth of cucumber seedlings was inhibited.The dry weight and chlorophyll content significantly decreased under 70mmol·L-1 Ca(NO3)2 stress.The activities of antioxidant enzyme,including SOD,POD,CAT and APX,increased in leaves and roots under stress.At the same time,the MDA and soluble protein content also increased.However,spraying with SNP,a nitric oxide donor,obviously alleviated the inhibition from Ca(NO3)2 stress,increased the dry weight of cucumber seedlings,activities of antioxidant enzyme,chlorophyll and soluble protein content in different extent,and markedly decreased the MDA content.The above results indicated that NO could enhanced the Ca(NO3)2 tolerance.Spraying with SNP had no obvious effects on cucumber seedlings under normal nutrient solution cultivation.