Effects of Ca ²⁺ and nitric oxide on growth and active oxygen metabolismof cucumber seedlings under NaCl stress

The study was conducted in a nutrient solution to investigate the effects of Ca 2+ on growth and active oxygen metabolism of cucumber seedlings induced by exogenous nitric oxide under the 50 mmol/L NaCl stress. The results show that plasma membrane Ca 2+ channel blockers La3+ block the effects on growth and active oxygen metabolism induced by exogenous nitric oxide. Exogenous nitric oxide or Ca2+ alleviate the injury to seedlings under the 50 mmol/L NaCl stress significantly, and the seedling growth, activities of SOD, POD and CAT are increased and the rate of O2- production, contents of MDA and H2O2 are decreased. These results indicate the La3+ blocks those effects induced by exogenous nitric oxide under the NaCl stress, and Ca 2+ might play an important role in growth and active oxygen metabolism induced by exogenous nitric oxide. The effect of nitric oxide here depends on the content of Ca 2+ in cytoplasm.