Phenotypic diversity and population structure of Ethiopian barley (Hordeum vulgare L.) landrace collections

Landraces play a key role in crop breeding by providing beneficial trait for improvement of related crops and their genetic diversity studies are very important for breeding program and identification of parental lines. In this study, 585 barley (Hordeum vulgare L.) landraces collected from 13 agro-ecological zones of Ethiopia were evaluated along with 10 cultivars for their phenotypic diversity and population structure in relation to agronomic traits, resistance to major diseases and barley shoot fly. Data on 22 agronomic traits, three major diseases and barley shoot fly resistance-related traits were recorded. Univariate and multivariate approaches such as principal component and cluster analyses were applied to assess the genetic diversity and population structure. The analysis of variance indicated significant genotypic main, accessions x year and accession x environment interaction effects for almost all the traits evaluated. However, the accessions x environment interactions were mainly due to changes in magnitude rather than crossover types of interactions. The diversity analysis indicated that the population was highly structured according to kernel row-type, region (geographic) origin and altitude classes. Since the population is highly structured, appropriate statistical models will be needed when this population is used for association mapping studies. Eight principal components (PCs) in principal component analysis (PCA) accounted for the variation of 83.01%. The most related traits were included in the same PC, implying that results from PCA could give clues as to the relationship among traits. Though variability existed within and among clusters, useful germplasm clustered together. These materials are important sources of germplasm for the improvement of agronomic, disease and insect pest resistance traits. Keywords: Barley, diseases, genetic diversity, landraces, multivariate, shoot fly