Effects of Exogenous Nitric Oxide on Main Growth and Physiological Characteristics of Seedlings of Cotton Under NaCl Stress

【Objective】The purpose of this study is to clarify the effects of nitric oxide(NO) on cotton seedlings growth and leaf physiological characteristics under NaCl stress.【Method】In a hydroponic experiment,two NaCl concentrations(50 mmol·L-1 and 100 mmol·L-1),four sodium nitroprusside(SNP) concentrations(0,50,100 and 200 μmol·L-1) for each NaCl level were designed,and at the same time a conventional culture was set.The growth and leaves physiological characteristics of cotton seedlings were measured after 10 days of treatment.【Result】The results showed that the treatment of NaCl stress inhibited the growth of cotton seedlings.The internodes of the cotton seedlings under NaCl stress were inhibited further by SNP which is an exogenous nitric oxide donor.The relative water content of cotton seedlings,especially the relative water content of the stem and root were decreased in SNP treatments under NaCl stress.The treatments of SNP added in 100 mmol·L-1 NaCl stress increased the contents of soluble protein and chlorophyll,and the ratio of chlorophyll a/b,the effects of 50 μmol·L-1 SNP was the best.Under both of the NaCl stresses,SNP improved the activities of SOD and POD significantly,while the activities of CAT decreased.【Conclusion】Under this experimental condition,exogenous nitric oxide inhibited internodes elongated,alleviated chlorophyll degradation,enhanced antioxidant capacity and improved leaves quality of cotton seedlings under NaCl stress.The SNP concentration from 50 μmol·L-1 to 100 μmol·L-1 could alleviate NaCl stress for cotton seedlings,the cotton seedlings under NaCl stress were seriously injured by high concentrations(200 μmol·L-1)of SNP.