Effects of exogenous nitric oxide on photosynthesis and ionic contents of tomato seedlings under NaCI stress

The effects of sodium nitroprusside(SNP，an exogenous nitric oxide donor)on photosynthesis and ionic contents in tomato(Lycopersicon esculentum Mill．)seedlings were investigated under 100 mmol/L NaCl stress．The results showed that under NaCl stress，chlorophyll contents，net photosynthetic rate(Pn)，stomatal conductance(Gs)，chlom． phyll fluorescence parameters Fv/Fm and Fv/Fo were significantly increased，but intercellular CO2 concentration(Ci)was obviously decreased by exogenous nitric oxide．At the same time，contents of K+、Ca2+ and Mg2+ in dry weight of mot and leaves were markedly increased，but contents of Na+ were significantly decreased by exogenous nitric oxide．The above results indicated that exogenous nitric oxide donor(SNP)could alleviate the unfavorable effects of NaCl stress on photosynthesis；delay the inhibition of tomato seedlings by NaCl stress．