Abstract: To better utilize alfalfa varieties and improve the efficiency and process of new variety selection,55 alfalfa varieties were used as materials in this study to analyze and evaluate agronomic and yield traits of alfalfa by coefficient of variation,genetic diversity index,correlation analysis,cluster analysis and principal component analysis. The results showed that the coefficients of variation of agronomic and yield traits were 6.89%~23.42%;the genetic diversity indexes 0.714 3~0.884 5 among which the highest diversity index was total leaf dry weight,while the lowest diversity index the stem-to-leaf ratio and fresh-to-dry ratio of the alfalfa varieties in second harvest. The 55 alfalfa varieties were divided into 3 main groups by cluster analysis,in which each group had obvious traits and characteristics;the varieties in group I and II need to be further mined for their excellent traits and can be utilized as complementary materials for breeding,and the varieties in group III can be directly introduced to the practical production,and can also be used as the parental materials in selection and breeding of highyield and good-quality varieties for the genetic improvement. Correlation and principal component analysis showed that number of branches,fresh-to-dry ratio,stem dry weight,leaf dry weight and plant height were the most important traits affecting the yield. The results of this study would provide a reference for the development and utilization of alfalfa varieties and the variety breeding of alfalfa in the semi-arid area.

Key words: Medicago sativa L., Trait, Diversity index, Comprehensive evaluation

摘要： 为更好利用紫花苜蓿品种材料，提高新品种选育效率，本研究以收集的55个紫花苜蓿品种为材料，通过利用变异系数、遗传多样性指数、相关性分析、聚类分析及主成分分析等方法对其主要农艺性状和产量性状进行分析和评价。结果表明，苜蓿品种的农艺性状和产量性状变异系数介于6.89%~23.42%，多样性指数介于0.714 3~0.884 5，多样性指数最高的是叶总干重，最低的是第二茬茎叶比和鲜干比。聚类分析将55个苜蓿品种划分为3大类群，类群Ⅰ、Ⅱ中的品种需进一步进行优良性状挖掘和作为互补材料进行育种利用，类群Ⅲ中的品种可直接引种进行生产，也可作为高产、优质品种选育中的亲本材料进行遗传改良。相关性和主成分分析得出，分枝数、鲜干比、茎干重、叶干重和株高是影响草产量的最主要因素。本研究的结果可为苜蓿品种的开发利用及半干旱区苜蓿品种选育提供参考。

关键词: 紫花苜蓿, 性状, 多样性指数, 综合评价