Abstract: The identification of salt tolerance at seedling stage plays an important role in the breeding of salt-tolerant alfalfa varieties. In this study, three alfalfa varieties ‘Daye’, ‘Gannong No.3’ and ‘Algonkin’ were subjected to nutrient solution treatments with NaCl concentrations of 0%, 0.3%, 0.6%, and 1.0%. The physiological index changes and differences in salt tolerance among the alfalfa seedlings were investigated, aiming to provide a foundation for breeding salt-tolerant varieties and utilizing saline-alkali land across different alfalfa cultivars. The results indicated that with the escalation of salt stress concentration, the root activity of the three alfalfa seedlings decreased gradually, the chlorophyll content initially increased and then decreased, and the contents of cell membrane permeability, proline, soluble sugar, and malondialdehyde increased along with the increase of salt stress. It was rational to assess the salt tolerance of alfalfa seedlings using nutrient solution with a salt concentration ranging from 0.6% to 1.0%. The comprehensive evaluation of salt-tolerance of three alfalfa varieties at seedling stage by principal component analysis and membership function method showed that the salt-tolerance of ‘Daye’ was the strongest,followed by ‘Algonquin’ and ‘Gannong No.3’.

Key words: Salt stress, Alfalfa, Seedling, Physiological characteristics, Comprehensive evaluation

摘要： 苗期耐盐性鉴定对紫花苜蓿（Medicago sativa L.）耐盐品种选育具有重要作用。本研究以‘大叶苜蓿’（Medicago sativa ‘Daye’）、‘甘农三号’（Medicago sativa ‘Gannong No.3’）和‘阿尔冈金’（Medicago sativa ‘Algonquin’）3个紫花苜蓿品种为实验材料,以NaCl含量为0,0.3%,0.6%和1.0%等浓度的营养液进行盐胁迫处理,研究各苜蓿幼苗生理指标的变化及耐盐性差异,旨在为不同品种紫花苜蓿耐盐性选育及盐碱地利用提供依据。结果表明：随着盐胁迫浓度的增加,3种紫花苜蓿幼苗的根系活力逐渐下降,叶绿素含量先增加后降低,细胞膜透性、脯氨酸、可溶性糖、丙二醛含量均随盐胁迫的增加而增加。0.6%~1.0%盐浓度的营养液用于鉴定紫花苜蓿幼苗耐盐性较为合理。主成分分析和隶属函数法对3个苜蓿品种苗期耐盐性的综合评价表明‘大叶苜蓿’的耐盐性最强,其次是‘阿尔冈金’,最后是‘甘农三号’。

关键词: 盐胁迫, 苜蓿品种, 幼苗, 生理特性, 综合评价