Abstract:In this article,the growth and physiological characteristics of cucumber seedlings were studied under treatments(14,56,98,140,182 mmol/L) of Ca(NO3)2,KNO3,NaNO3 and NaCl.The results showed that with increasing concentration of NO-3,the growth of cucumber seedlings was inhibited,the membrane permeability was obviously increased,proline content was increased,but the effects of different salt treatments on the activity of protective enzymes were different. The effects of three kinds of NO3--N fertilizer on cucumber seedlings followed the order that Na+ >K+>Ca2+.At the same level of Na+,the effect of NaNO3 was greater than NaCl on cucumber seedlings growth.