Abstract: This study was aimed to investigate the effects of 2,4-epibrassinolide (EBR) on physiological indexes and root ion accumulation of Medicago sativa under salt stress in artificial climate chamber. The results showed that 150 mmol·L^-1 salt stress significantly inhibited the growth of alfalfa. When the concentration of exogenous hormone EBR was 0.6 μmol·L^-1 (M2),the activities of superoxide dismutase (SOD),catalase (CAT),peroxidase (POD) and soluble protein content were significantly increased,and malondialdehyde (MDA) was decreased,The results showed that 0.6 μmol·L^-1 (M2) and 1.2 μmol·L^-1 (M3) treatments significantly reduced the toxicity of Na⁺ to K⁺,Ca²⁺,Mg²⁺ and controlled the ion balance;therefore,exogenous hormone EBR could reduce the damage of salt stress to roots and enhance the activity of root antioxidant system.

Key words: 2,4-brassinolactone, Alfalfa, NaCl stress, Physiological characteristics, Ion metabolism

摘要： 为探讨2，4-表油菜素内酯（2，4-Epibrassinolide，EBR）对紫花苜蓿受盐胁迫的影响，本试验以紫花苜蓿‘阿迪娜’为材料，采用人工气候室水培试验，研究盐胁迫条件下喷施不同浓度的外源激素EBR对紫花苜蓿生理指标和根系离子积累的作用。结果表明：150 mmol·L^-1盐胁迫对苜蓿生长具有明显的抑制作用，当喷施外源激素EBR浓度为0.6 μmol·L^-1时，可显著提高超氧化物歧化酶（Superoxide dismutase，SOD）、过氧化氢酶（Catalase，CAT）、过氧化物酶（Peroxidase，POD）活性和可溶性蛋白含量，降低丙二醛（Malondialdehyde，MDA）含量和电解质渗透率；0.6 μmol·L^-1和1.2 μmol·L^-1EBR处理显著减轻Na⁺对K⁺，Ca²⁺，Mg²⁺的毒害，控制离子平衡。由此可见，外源激素EBR可以减小盐胁迫对根系的伤害，增强根系抗氧化系统活性。

关键词: 2，4-表油菜素内酯, 紫花苜蓿, NaCl胁迫, 生理特性, 离子代谢