水杨酸对低温胁迫种子萌发及细胞膜稳定性的影响

Effects of SA on the germination of seeds and the stability of cell membrane under cold stress

【目的】研究水杨酸（SA）对-5℃低温胁迫种子萌发及幼苗细胞膜稳定性的影响。【方法】以二色胡枝子、达乌里胡枝子、西农889、西农979、小堰6号和小堰22种子为材料，用浓度为0（CK），0．005，0．05，0．1，0．5，5mmol／L的SA浸种，经5℃低温胁迫处理24h后于室温下培养，4d后测定发芽势，8d后测定发芽率、发芽指数、活力指数及幼苗电导率和丙二醛（MDA）含量。【结果】随着SA处理浓度的增加，种子的发芽率、发芽势、发芽指数和活力指数均呈现“先上升后降低”的变化趋势，而幼苗的电导率和MDA含量则呈现出“先降低后上升”的变化趋势。二色胡枝子、达乌里胡枝子、西农889、西农979、小堰6号和小堰22等6种植物种子在-5℃低温胁迫后，萌发所需的最适SA处理浓度分别为0．05～O．1，0．1～0．5，0．01～0．5，0．005～0．5，0．005～0．05和0．1mmol／L。【结论】低浓度的SA能够抑制细胞膜脂过氧化，保持细胞膜的完整性，减缓植物种子的低温伤害，促进低温胁迫后的种子萌发；而高浓度的SA对低温胁迫种子的萌发具有抑制作用，不同植物种子萌发所需要的SA处理浓度不同。

[Objective] We studied the effects of SA on the germination of seeds under cold stress（--5 ℃ ）and stability of cell membrane of seedlings. [Method] The seeds of Lespedeza bicolor, lespedeza da- vurica,Xinong 889, Xinong 979,Xiaoyan 6 and Xiaoyan 22 were studied in this paper. The six kinds of plant seeds were soaked in SA and subject to cold stress （--5 ℃）for 24 hours,then cultured under normal temperature and the seed germination power was determined four days later and germination rate,germination index,vigor index, relative conductivity and MDA content of seedlings were determined eight days later. [Result] As the concentration of SA increased, the germination rate, germination power, germination index and vigor index of seeds increased first but followed by decrease. Relative conductivity and MDA con- tent decreased first and then increased. The most suitable concentrations of SA that would alleviate the strong cold stress（--5 ℃ ） to the seeds of Lespedeza bicolor ,lespedeza davurica, Xinong 889 ,Xinong 979, Xiaoyan 6 and Xiaoyan 22 were 0.05--0. 1,0. 1- 0. 5,0. 01- 0. 5,0. 005--0. 5,0. 005- 0. 05 and 0. 1 mmol/L respectively. [Conclusion] SA in low concentration can reduce the lipid peroxidation, keep the integrity and stability of cell membrane to relieve the harm of cold stress and promote the germination of seeds. SA in high concentration can inhibit the germination of seeds under low temperature. Different SA concentrations are appropriate for different kinds of plants.