Abstract:

Detecting the diversity of germplasm collection is important to plant breeders for utilizing and management the collection efficiently and effectively. A total number of 87 prairie grass(Bromus catharticus) accessions with worldwide geographic origins were studied in field at the Yaan city of Sichuan province, and nine phenotypic characters were recorded. According to the coefficients of variation, all studied characteristics showed a high degree of variability, but it were highly pronounced for dry matter per plant, tiller number and leaf width. The majority of significant correlation coefficients were found in the traits representing plant size. Steam diameter and length of first internode had significantly positive correlations(P<0.01) with others, and the correlation coefficient between length of second upper leaf and breadth of flag leaf was the highest one(r=0.912,P<0.01). Principal component analysis(PCA) was performed for phenotypical diversity determination and grouping of germplasm collections. Two principal components were found to explain 74% of the total variation in the dependence structure. Plant size characters together with tiller number appeared to be the major sources of diversity among B. catharticus accessions. Based on the cluster analysis using UPGMA method, accessions included in three main clusters, first group had large plant size with broad leaves, wider stems and medium tillers number, second had medium plant size, and third had small size with narrow leaves and large tillers number. Scatter plot using two first principal component scores also confirmed the grouping by cluster analysis. Overall, the study demonstrates that B. catharticus is a highly versatile forage species and the quantitative trait diversity in the germplasm has significance for forage grass breeding programs and future collecting strategies.

Key words: Bromus catharticus, Morphological trait, Variability, Germplasm, Diversity

摘要：

检测种质资源的多样性对于利用和有效管理种质非常重要。本研究对87份世界来源的扁穗雀麦种质利用常用的9个形态-农艺性状进行了统一田间评价。结果表明,所有采用的性状变异系数均表现出高度的变异,尤其以单株干物质产量、分蘖数和叶宽的变异幅度最大。反映株型大小的各性状之间呈显著相关,茎粗和第一节间长与其余8个性状之间存在显著相关(P<0.01),旗叶宽与倒二叶宽的正相关性最强(r=0.912,P<0.01)。主成分分析(PCA)表明前2个主成分可以解释总变异的74%。反映株型大小的性状以及分蘖数可能是扁穗雀麦种质形态变异的主要来源。基于欧氏距离的UPGMA聚类分析将供试材料分成3个主要的类群,第一类群具有最大的株型表现,茎干粗壮,旗叶和倒二叶宽大,分蘖数中等;第二类群具有中等的株型;第三类群具有较小的株型,叶片短而窄,但分蘖数较多。聚类分析很好地支持了前2个主成分分值的二维散点图的结果。总之,本研究表明扁穗雀麦是一种在西南平原和丘陵地区适应性极强的禾草,其表型多样性对于品种选育和资源收集具有重要的参考价值。

关键词: 扁穗雀麦, 形态性状, 变异, 种质, 多样性