Abstract: To evaluate the differences in salt tolerance among different alfalfa （Medicago sativa L.） cultivarsunder salt stress conditions and screen high-quality salt-tolerant germplasm resources，this study used 25 alfalfa cultivars as experimental materials， with two treatments of salt stress （200 mmol·L^-1 NaCl solution）and control （ultrapure water）. Germination and growth parameters were measured during the germination period （eight indicators， such as germination energy and germination rate， etc.） and seedling stage （six indicators， such as plant height and branch number， etc.）， and a comprehensive evaluation of salt tolerance was conducted using methods such as membership function value， comprehensive salt tolerance （D value）， and cluster analyses. The results showed that salt stress significantly reduced all germination parameters， with the seed vigor index exhibiting the highest reduction rate （-92.26%）， whereas the seedling dry weight was the least affected （-11.76%）. Cluster analysis classified the 25 alfalfa cultivars into five salt tolerance grades at the germination stage： included 2 of the strongest salt-tolerant cultivars， 4 strong salt-tolerant cultivars， 5 moderate salt-tolerant cultivars， 10 weak salt-resistance cultivars， and 4 salt-sensitive cultivars. Further evaluation of salt tolerance of 12 representative alfalfa cultivars during the seedling stage revealed salt stress had extremely significant effects on the plant height， above-ground fresh weight， relative water content， and electrical conductivity of alfalfa （P<0.01）， with significant differences between cultivars. By integrating the indicators of both germination and seedling stages， the three strongest salt-tolerant cultivars， namely ‘Xinmu No.4’‘Zhongmu No.4’， and ‘Bara520YQ’， were ultimately selected as important germplasm resources for salt-tolerant breeding and cultivation in saline-alkali soil regions.

Key words: Medicago sativa L., Seed germination, Seedling stages, Salt tolerance, Comprehensive evaluation

摘要： 为评价不同紫花苜蓿（Medicago sativa）品种盐胁迫下的耐盐性差异，筛选优质耐盐种质资源。本研究以25份苜蓿品种为材料，设置200 mmol·L^-1 NaCl盐胁迫和超纯水对照处理，测定萌发期（发芽势、发芽率等8项）及苗期（株高、分枝数等6项）参数，采用隶属函数、综合耐盐值D及聚类分析进行综合评价。结果显示：盐胁迫显著降低所有萌发参数，种子活力指数降幅最大（-92.26%），幼苗干重受影响最小（-11.76%）；聚类分析将萌发期25份材料划分为5个耐盐等级，含2份强耐盐、4份较强耐盐、5份中等耐盐、10份弱耐盐及4份盐敏感品种。对12份代表性品种苗期评价发现，盐胁迫对株高、地上鲜重、叶片相对含水量及电导率影响极显著（P<0.01），且品种间差异显著。整合萌发期与苗期指标，最终筛选出‘新牧4号’‘中苜4号’和‘Bara520YQ’3个强耐盐品种，可作为耐盐育种及盐碱地栽培的重要种质资源。

关键词: 紫花苜蓿, 种子萌发, 苗期, 耐盐性, 综合评价