Abstract: In order to find out the alleviating effect of exogenous methyl jasmonate (MeJA) on salt damage of alfalfa seedling,Medicago sativa ‘Pianguan’ was used as experiment material,and germination test was adopted. This study analyzed the effects of different MeJA concentrations (0.025,0.25,2.5,25 and 250 μmol·L^-1) and soaking times (3,6,9,12 and 24 h) on the germination percentage (GP),germination index (GI),seedling vigor index (SVI),mean germination time (MGT),relative water content (RWC),root length (RL) and shoot length (SL) of Medicago sativa ‘Pianguan’ under salt stress (NaCl). The comprehensive evaluation of multiple indexes was carried out using the method of membership function. The results showed that under 150 mmol·L^-1 NaCl stress,MeJA pretreated seeds could alleviate the salt damage to varying degrees. MeJA at the concentration of 25 μmol·L^-1 and soaking for 3 hours was the optimal treatment combination,which had the best benefit on the germination of Medicago sativa ‘Pianguan’ seed under salt stress,and significantly improved the GP,GI,SVI and SL of seeds (P<0.05),but had no effect on MGT,RWC or RL of seedlings. This study provides reference and guidance for the rational use of MeJA in stress-resistance cultivation of alfalfa at seedling stage.

Key words: MeJA, Salt stress, Medicago sativa ‘Pianguan’, Seed germination

摘要： 为明确外源茉莉酸甲酯（methyl jasmonate，MeJA）对紫花苜蓿苗期盐害的缓解效应，本研究以偏关苜蓿（Medicago sativa ‘Pianguan’）为供试材料，采用发芽试验的方法，探讨不同施用浓度（0.025，0.25，2.5，25和250 μmol·L^-1）和浸泡时间（3，6，9，12和24 h）的MeJA处理对盐胁迫（NaCl）下偏关苜蓿的发芽率（germination percentage，GP）、发芽指数（germination index，GI）、幼苗活力指数（seedling vigor index，SVI）、平均发芽时间（mean germination time，MGT）、相对含水量（relative water content，RWC）、根长（root length，RL）和芽长（shoot length，SL）的影响，并利用隶属函数法进行多指标综合性评价。结果表明：在150 mmol·L^-1 NaCl胁迫下，MeJA预处理种子能不同程度地缓解盐害，而且浓度为25 μmol·L^-1的MeJA浸种3 h为最佳处理组合，对盐胁迫下偏关苜蓿种子萌发的促进效果最好，其显著提高了种子的GP，GI，SVI和SL（P<0.05），但是对MGT，RWC和RL影响不显著。本研究为MeJA在苜蓿幼苗阶段耐逆栽培中的合理使用提供参考和指导。

关键词: MeJA, 盐胁迫, 偏关苜蓿, 种子萌发