Effect of exogenous Ca2+ and NO donor SNP on seed germination and antioxidase activities of Perilla frutescens seedlings under NaCl stress

OBJECTIVE: In order to find a method for improving the salt resistance of seeds and seedlings for Perilla frutescens under NaCl stress, seed germination and physiological characteristics of P. frutescens seedlings were studied. METHOD: Several physiological indexes of P. frutescens seeds treated by Ca2+ and sodium nitroprusside (SNP) under NaCl stress like the germination vigor, germination rate, germination index and vigor index were measured. And other indexes like the biomass of the seedlings, the content of malondialdehyde (MDA) in leaves, the activities of superoxide (SOD), peroxidase (POD) and catalase (CAT) were also measured. RESULT: The germination of P. frutescens seeds under NaCl stress was inhibited obviously. But after the treatment with Ca2+ and SNP, all of the germination indexes increased. And the seeds that treated with SNP + Ca2+ had the most significantly increase in all indexes. The germination vigor was 65.1%, the germination rate was 89.3%, the germination index and vigor index were 13.9 and 0.1109, respectively. The content of MDA decreased after the treatment. The activities of three enzymes include SOD, POD and CAT were increased by the treatment and get the maximin 0.84, 5.71 and 4.92 U x mg(-1) respectively. And the EGTA showed an obvious inhibition to the effect of SNP on P. frutescens. CONCLUSION: SNP (0.1 mmol x L(-1)) and Ca2+ (10 mmol x L(-1)) could significantly alleviate the damages to the seeds and seedlings of P. frutescens under NaCl stress, and promote the salt resistance of the seeds and seedlings. These results might suggest that exogenous NO might enhance P. frutescens salt resistance and alleviate salt injury possible by enhancing Ca2+ influx by activating Ca2+ channels and improving concentration of Ca2+ of P. frutescens seedlings.