Genetic diversity of Bromus inermis on agronomic traits

132 germplasms of Bromus inermis were employed for phenotypic diversity analysis using 31 agronomic traits. High polymorphism was detected among materials from different origins. Variation coefficient ranged from 9% to 105%. Agronomic traits with larger variation were ratio of stem biomass to leaves biomass, anther length, length of the first joint of panicle, yield per plant, seeds yield, length of spikelet, moisture content, hay yield, fresh yield, number of spikelet,etc. The results of principal component analysis showed that the 19 principal components, including plant height, hay yield, fresh yield, stalk diameter, moisture content, length and width of spikelet, 1 000seed weight, number of spikelet, number of stem of panicle, length of the second glume, length of the first joint of panicle, length and width of panicle, number of blade, number of culm joint, length of base branch, ratio of hay yield to fresh yield and yield per plant, were the main factors for agronomic variation, and the cumulation of first 14 principal components contributed 86.22% of variation. Cluster analysis based on the agronomic traits showed that all of these traits could be divided into four groups: width of seeds alone together for a group; the second group consisting of traits of anther length and ratio of stem biomass to leaves biomass; the third group comprising traits of length of the first glume, length of the second glume, length of panicle, and length of seeds; the rest clustered into the fourth group. Cluster analysis based on 132 germplasms were divided into nine groups: 1) higher fresh yield; 2) more number of blade and number of spikelet; 3) smaller ratio of stem biomass to leaves biomass; 4) and 5) more 1 000seed weight; 6) higher plant height; 7) and 8) poor agronomic traits; and 9) higher seeds yield per 10 m2. The results of this study have provided an important theory basis for B. inermis breeding and varietal improvement.