Abstract: To comprehensively evaluate the differences in cadmium tolerance of different alfalfa （Medicago sativa L.） germplasms during seed germination， the indicators related to seed germination and seedling growth of 40 cultivars were measured under two conditions of control （distilled water） and cadmium stress （50 μmol·L^-1 CdCl₂） in this study. Based on the comprehensive indicator weight， membership function analysis and comprehensive evaluation value （D value）， the cadmium tolerance of the tested alfalfa germplasms was comprehensively analyzed. The results indicated that 50 μmol·L^-1 cadmium solution had inhibitory effects on nine indicators including seed vigor index， root length， and seedling vigor index of the tested alfalfa cultivars， with root length being the most inhibited. Based on the comprehensive evaluation of cadmium tolerance D value and systematic clustering analysis， the cadmium tolerance of 40 tested alfalfa germplasms was divided into three categories， namely strong cadmium tolerance （D≥0.691）， medium cadmium tolerance （0.691>D≥0.468） and weak cadmium tolerance （0.468>D）. The cultivars with the strongest and weakest cadmium tolerance were selected as ‘Bara520YQ’ and ‘WL298HQ’， respectively. This study provides a theoretical reference for screening and utilization of new germplasms of alfalfa with cadmium tolerance， the mining of cadmium tolerance genes， and the exploration of molecular regulatory mechanisms.

Key words: Alfalfa, Seed germination, Cadmium tolerance, Comprehensive evaluation, Cluster analysis

摘要： 为综合评价种子萌发期不同紫花苜蓿（Medicago sativa L.）种质的耐镉性差异，本试验测定了40个品种在对照（蒸馏水）和镉胁迫（50 μmol·L^-1 CdCl₂）两种条件下种子萌发与幼苗生长相关指标，并基于综合指标权重、隶属函数分析和耐镉性综合评价D值对供试紫花苜蓿种质进行耐镉性综合分析。结果表明：50 μmol·L^-1镉溶液对供试紫花苜蓿品种的种子活力指数、根长、幼苗活力指数等9个指标均有抑制作用，其中根长所受抑制程度最大。结合耐镉性综合评价D值和聚类分析，40个供试紫花苜蓿种质耐镉性被划分为强耐镉性（D≥0.691）、中耐镉性（0.691>D≥0.468）和弱耐镉性（0.468>D）3大类，并筛选出耐镉性最强和最弱的品种分别为‘Bara520YQ’和‘WL298HQ’。本试验为紫花苜蓿耐镉性新种质的筛选与利用、耐镉基因挖掘及分子调控机制探索提供了理论参考。

关键词: 紫花苜蓿, 种子萌发, 耐镉性, 综合评价, 聚类分析