WU Changzhong, PAN Wenxuan, ZHAO Yan, YAN Weihong, HUO Chunran, YAN Wenhao, LI Zhiyong, WU Zinian
Using 370 Agropyron germplasms as experimental materials, this study systematically investigated their genetic diversity using 31 phenotypic traits and multiple statistical methods, including coefficient of variation, genetic diversity index, cluster analysis, correlation analysis, and grey relational analysis. Additionally, QGA software was employed to simulate and analyze genetic distance, sampling ratio, and clustering algorithms to determine optimal parameters for core germplasm construction. The effectiveness of the core subset was verified through principal component analysis and genetic diversity parameters. Results indicated significant phenotypic differentiation and rich genetic diversity in Agropyron germplasms. Quantitative traits (23 in total, with an average diversity index of 1.867) served as the primary carriers of genetic diversity, with their genetic diversity index was significantly higher than that of qualitative traits (1.328). Phenotypic correlations revealed a "source-sink-flow" coordinated development mechanism: leaves and stems exhibited coordinated growth; spike length was positively correlated with spikelet and floret numbers but negatively correlated with spikelet density, providing a basis for ecological adaptive breeding. Cluster analysis categorized the materials into three characteristic germplasm types: Type Ⅰ (24 resources, characterized by tall plants, long roots, and long spikes), Type Ⅱ (123 resources, emphasizing spike and leaf development), and Type Ⅲ (223 resources, with high spikelet density and numerous glume veins). Grey relational analysis identified seven core evaluation indicators: spikelet number, florets per spike, spike width, first rachis internode length, leaf color, leaf sheath length, and second internode stem diameter. Fifteen comprehensively excellent materials (GB3, BB34, MB15, BB55, XB6, MB25, MB32, GB11, MB7, SB55, SB52, BB68, XB3, BB110, XB2) were selected. A core germplasm consisting of 92 accessions was constructed using "Mahalanobis distance+deviation sampling+sum of squared deviations+25% sampling ratio." This core subset included all 15 excellent materials, achieving an organic unity of genetic diversity conservation (MD=0, CR=100%) and superior trait screening (VD=41.935%, VR=115.413%). Principal component analysis confirmed high consistency between the core germplasm and the original population in genetic structure (core germplasm cumulative contribution rate: 73.014%; original population: 64.407%). This study integrates phenotypic diversity analysis, grey relational evaluation, and core germplasm construction techniques, providing theoretical basis and material support for the efficient utilization and genetic improvement of Agropyron germplasm resources.