Effects of exogenous nitric oxide on growth of cotton seedlings under NaCl stress

In the present investigation, the role of sodium nitroprusside (SNP, a donor of NO) in inducing salinity tolerance (100 mM NaCl) in cotton was studied. Salt stress reduced the values of photosynthetic attributes and total chlorophyll content and inhibited the activities of nitrate reductase. Furthermore, salt stress also induced oxidative stress as indicated by the elevated levels of lipid peroxidation compared to CK. The application of SNP at 1.00 mM promoted the growth and restrained superoxide anions (O-2(center dot-)) generation rate. And activities of antioxidant enzymes, namely, catalase (CAT) and superoxide dismutase (SOD), were enhanced by SNP treatment. On the other hand, an increase in the K+ content, antioxidant enzyme activities, along with a decrease in the Na+/K+ ratio, the contents of thiobarbituric acid reactive substances (TBARS) and malondialdehyde (MDA) were observed in the NaCl-stressed seedlings subjected to the low level (0.1 mM) SNP. These results indicated that the application of moderate SNP can be used to protect plants growth and induce its antioxidant defense system under salt stress.