Effects of H_2O_2 Pretreatment on Distribution of K~+,Na~+ and Cl~- in Cucumber Seedlings under Salt Stress

Taking the seedlings of cucumber(Cucumis sativus L.) cultivar Jinchun No.2 as experimental material,the effects of H2O2 pretreatment on contents of K+,Na+ and Cl-in different organs were studied by the method of hydroponics.The results showed that under salt stress,the K+ content decreased while Na+ and Cl-contents increased in cucumber seedlings,so the ratios of K/Na and Cl/Na all decreased.Compared with the seedlings treated with salt stress only,cucumber seedlings treated with exogenous H2O2 combined with salinity showed higher levels of K+ accumulation in all the organs and lower levels of Na+ and Cl-in leaves.For salt-stressed cucumber seedlings,the supplement of exogenous H2O2 increased the absorbing and transporting selectivity ratio of K+ to Na+,increased K/Na ratio,and alleviated damage of salt stress,enhanced seedling growth,increased significantly dry weight of root,stem and leaf and shoot height.In conclusion,exogenous foliar spraying H2O2 could improve the tolerance of cucumber seedlings to salt stress by regulating the ionic compartmentalization in organs.