Effects of Salicylic Acid on Several Physiological Indexes Related to Cold Resistance of Cucumber Seedling Leaf Under Low Temperature Stress

Using cucumber 'Jinyan-2' as the material,the effects of different concentrations of salicylic acid on the growth of cucumber seedling under 4℃ cold stress were studied by hydroponic culture.The results showed that under cold stress,the contents of chlorophyll and soluble proteins were significantly decreased than those of control.The contents of proline,soluble sugar,MDA and the activities of SOD and POD were significantly increased(P0.01).Exogenous SA application on the root significantly increased the contents of chlorophyll,soluble proteins,soluble sugar and proline,while the activities of SOD and POD were significantly increased,the membrane lipid peroxidation products MDA content decreased significantly(P0.01).Therefore,the application of SA could improve the conptents of cucumber seedling soluble protein,soluble sugar and Pro and the activities of SOD and POD to maintain the stability of cell membrane,decrease membrane lipid peroxidation damage degree,so as to alleviate the low temperature stress on seedling growth inhibition,and the alleviated effect was the best under the condition of 1.5 mmol/L exogenous SA.