亚精胺对盐胁迫下紫苏种子萌发和幼苗生理特性的影响

目的 通过对紫苏种子萌发和幼苗生理特性的研究，寻找提高紫苏种子及幼苗在盐胁迫条件下的抗盐能力的方法。方法 测定不同浓度亚精胺（Spd）处理后的盐胁迫下紫苏种子的发芽势（G_v）、发芽率（G_r）和发芽指数（G_i），并对紫苏幼苗叶片的相对含水量、丙二醛（MDA）和超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性进行了测定。结果 盐胁迫下的紫苏种子萌发受到显著抑制，但是经过不同浓度的Spd处理后，萌发指标均有所升高，其中经过0.25 mmol/L Spd处理，各项指标均达到最大，G_v为59.7%，G_r为69.4%，G_i为12.8。Spd处理减缓了盐胁迫下紫苏叶片的相对含水量和总黄酮降低的趋势，并且降低了叶片MDA的量。Spd处理后SOD、POD和CAT 3种酶的活性均有所增加，但在Spd为0.25 mmol/L时达到最大值，分别为72.4 U/g、8.7 U/mg、8.8 U/mg。结论 0.25 mmol/L的Spd能够有效地减缓盐胁迫对紫苏种子及幼苗产生的伤害，提高了种子及幼苗的抗盐能力。

Effect of spermidine on seed germination and physiological characteristics of Perilla frutescens seedlings under NaCl stress

Objective In order to get the method for improving the salt resistance of Perilla frutescens seeds and seedlings under NaCl stress, the seed germination and physiological characteristics of P. frutescens seedlings were studied. Methods Several physiological indexes of P. frutescens seeds under NaCl stress, such as the germination vigor (G_v), germination rate (G_r), and germination index (G_i), were measured. And other indexes of the seedlings like relative water contents (RWC), malondialdehyde (MDA), superoxide (SOD), peroxidase (POD), and catalase (CAT) were also measured. Results The germination indexes of P. frutescens seeds under NaCl stress was inhibited obviously inhibition. But after the treatment by spermidine (Spd) at the different concentrations, every germination indexes were all increased. And the seeds treated by Spd with the concentration of 0.25 mmol/L had the most significant increase in every index. The G_v was 59.7%, the G_r and G_i were 69.4% and 12.8, respectively. The RWC and total flavonoids in P. frutescens leaves decreased under NaCl stress, but after treated by Spd, the rate of decrease had been relieved and the content of MDA was decreased. The activities of three enzymes including SOD, POD, and CAT were increased by the treatment of Spd, and got the maximum (72.4 U/g, 8.7 and 8.8 U/mg, respectively) with the concentration of 0.25 mmol/L were got. Conclusion Spd with the concentration of 0.25 mmol/L could significantly alleviate the damages to the seeds and seedlings of P. frutescens under NaCl stress,and promote the salt resistance to the seeds and seedlings of P. frutescens.