The investigation of the genetic variability for yield and morphological and seedling characteristics in of Bromegrass populations

In order to study the genetic variability in populations of two species of Bromus tomentellus and Bromus inermis for yield, morphological and seedling characteristics, 18 populations were examined in the field and germinator during 2006-2008 in Tehran Iran. The data were collected for heading date, plant height, tiller number, panicle length, forage yield, seed yield, and seedling traits (seed germination, speed of germination, seedling length and vigor index). Results showed significant differences between two species for all of traits except seed germination percent The B.tomentellus populations had higher values for all of seed characteristics; in contrast, B.inermis had higher values for yield and morphological traits. Estimates of broad sense heritability were high for all of traits ranged from 0.42 to 0.99. Both seed and yield had positively correlated with heading date, plant height, tiller number and panicle length and negatively correlated with thousand seeds weight. Using principal components analysis, the first three components accounted for 82% of total variation. The first principal component indicated that, Forage yield and seed yield couple with late maturity and plant height were important traits. In the second component, germination traits and in third one the tiller density and panicle length were the most important traits for classification of genotypes. Using cluster analysis (Ward method) the 18 genotypes were classified correctly into two groups as belonged to the same species. The distributions of genotypes based on (PCA) analysis were in agreement with cluster analysis.