Abstract: This study focused on 194 Agropyron cristatum （crested wheatgrass） germplasm resources from diverse geographic origins. To assess phenotypic diversity and screen elite germplasm， we employed a suite of analytical methods including coefficient of variation （CV）， genetic diversity index， cluster analysis， principal component analysis （PCA）， correlation analysis， and grey relational analysis， based on 28 key phenotypic traits. Additionally， we used QGA software to analyze genetic distance， sampling proportion， and clustering methodologies， aiming to identify the optimal strategy for constructing a core germplasm collection. The reliability and representativeness of the resulting core set were rigorously verified. The results demonstrated that：statistical analysis of 28 phenotypic traits in 194 accessions of Agropyron cristatum （crested wheatgrass） revealed substantial phenotypic variation. The coefficient of variation （CV） ranged from 17.02%-87.85%， and the genetic diversity index （Shannon-Wiener index， H'） varied from 0.500-2.103. For qualitative traits （e.g.， spike shape， glume color）， the CV spanned 24.43%-52.75%， with an average H' of 0.869—indicating moderate diversity. For quantitative traits （e.g.， plant height， spike length）， the CV was broader （17.02%-87.85%）， and all H' values exceeded 1.524 （average： 1.962）， which reflected high genetic diversity. The results demonstrated that A. cristatum possesses rich genetic diversity， providing a solid foundation for elite germplasm selection and breeding programs.The grey relational analysis （GRA） demonstrated that spike length， spike width， spikelet number， length of the first rachis internode， spikelet color， flag leaf width， leaf sheath length， plant color， and other morphological traits served as key indicators for the comprehensive evaluation of Agropyron cristatum （L.） Gaertn. germplasm resources. A set of elite germplasm accessions （B61， B1， B37， B83， B164， B193， B48， and B85） were identified through screening. All of the accessions are incorporated into the core collection， thereby providing a scientific basis for the construction of a representative core germplasm set. Multivariate analysis integrating principal component analysis and QGA software optimization demonstrated that the combination of Euclidean distance metrics， multiple clustering priority sampling， single linkage method with a 25% sampling proportion constituted the optimal strategy for core germplasm construction in Agropyron cristatum （L.） Gaertn. （MD=0%， CR=100%， VD=25%， VR=113.474%）. The resultant core collection comprising 48 accessions exhibited a significantly higher cumulative contribution rate （75.54%） compared to the original population ， while maintaining 100% of the original genetic diversity. This scientifically validated core set provides a robust foundation for germplasm utilization and genetic improvement in crested wheatgrass.

Key words: Agropyron cristatum （crested wheatgrass）, Phenotypic traits, Genetic diversity, Core germplasm, Comprehensive evaluation

摘要： 本研究针对194份不同来源扁穗冰草（Agropyron cristatum）种质资源，利用变异系数、遗传多样性指数、聚类分析、主成分分析、相关性分析和灰色关联法等方法，基于28个表型性状进行多样性评估，并筛选出优异种质资源。进而结合QGA软件分析遗传距离、取样比例和聚类方法，探讨核心种质构建最佳策略，并检验其可靠性和代表性。结果表明：194份扁穗冰草种质资源28个表型性状统计分析显示：变异系数为17.02%~87.85%，遗传多样性指数介于0.500~2.103。质量性状的变异系数为24.43%~52.75%，遗传多样性指数平均为0.869；数量性状的变异系数为17.02%~87.85%，遗传多样性指数均大于1.524，平均为1.962；这表明扁穗冰草具有较高遗传多样性。灰色关联法分析获得的穗长、穗宽、小穗数、穗轴第一节间长、小穗颜色、旗叶宽、叶鞘长度、植株颜色等可以作为扁穗冰草种质资源综合评价主要指标。筛选出优异种质资源编号B61，B1，B37，B83，B164，B193，B48，B85，均包含在核心种质中，为核心种质的构建提供了依据。主成分与QGA软件综合统计分析确定“欧式距离+多次聚类优先取样法+最短距离法+25%取样比例”是扁穗冰草核心种质构建的最佳策略，其MD值为0%、CR值达100%、VD值为25%、VR值为113.474%。最终获得的48份核心种质其累计贡献率（75.54%）显著高于原始群体，完整保留了原始种质的遗传多样性，为扁穗冰草种质资源的高效利用与遗传改良提供了理想材料。

关键词: 扁穗冰草, 表型性状, 遗传多样性, 核心种质, 综合评价