Effects of salicylic acid on activities of protective enzymes and contents of osmotic adjustment substances of tomato seedlings during NaCl stress.

In order to clarify the protective effects of salicylic acid(SA)on leaf oxidative damage in 100 mmol·L-1 NaCl stressed tomato(Lycopersicon esculentum Mill.),the effect of SA(0,100,300,500 mg·L-1) on the leaf protective enzymatic activities and contents of osmotic adjustment substances in tomato seedlings were investigated.The results showed that the leaf activities of SOD,CAT and POD,contents of free praline,soluble protein,soluble sugar and MDA in leaves were significantly increased.SA pretreatment increased significantly the activities of SOD,CAT and POD,contents of free praline,soluble protein,soluble sugar and decreased MDA content.The best effect was observed in the treatment of 500 mg·L-1 SA.At the highest value,the activities of SOD,CAT and POD increased by 27.83%,29.52 % and 64.79%,contents of free praline,soluble protein and soluble sugar increased by 32.39%,51.39% and 13.57%,content of MDA decreased by 11.41% in comparison with seedling treated with NaCl stress only.The results showed that the best effect on the alleviation of NaCl stress damage was observed in the treatment of 500 mg·L-1 SA.The exogenous SA could play an important role in NaCl-tolerance of tomato seedlings by osmotic regulation,antioxidation,water balance and membrane stability.