Background Ethiopia is considered as center of diversity for barley (Hordeum vulgare L.) and it is grown across different agro-ecologies of the country. Unraveling population structure and gene flow status on temporal scales assists an evaluation of the consequences of physical, demographic and overall environmental changes on the stability and persistence of populations. This study was to examine spatial and temporal genetic variation within and among barley landrace samples collected over a period of four decades, using simple sequence repeat markers. Results Results from STRUCTURE, neighbor joining tree and discriminant analysis of principal component (DAPC) analysis revealed presence low-to-high genetic diversity among the landraces and grouped the landraces into three clusters. The cluster analysis revealed a close relationship between landraces along geographic proximity with genetic distance increases along with geographic distance. From analysis of molecular variance (AMOVA) in terms of collection year, it was observed that within-population genetic diversity much higher than between population and that the temporal differentiation is considerably smaller. The low-to-high genetic differentiation between landraces could be attributed to gene flow across the region as a consequence of seed exchange among farmers. Conclusion The results demonstrate that this set of SSRs was highly informative and useful in generating a meaningful classification of barley germplasms. Furthermore, results obtained from this study also suggest that landraces are a source of valuable germplasm for sustainable agriculture in the context of future climate change and in situ conservation strategies following adaptation to local environments.

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Barley (Hordeum vulgare L.) is Ethiopia's most important highland cereal crop and widely growing in most part of the country. Based on high levels of genetic and phenotypic diversity, the country is considered as center of diversity for barley. Assessments of the amount of genetic variation within and among populations are crucial for effective and efficient genetic improvement of the crop. Hence, this study was conducted to assess the diversity of barley landraces collected from various altitudes and regions of Ethiopia. A total of 585 barley landraces and 10 checks were evaluated using augmented randomized complete block design consisting of six blocks. All the 585 landraces were planted in un-replicated plots and the 10 checks were replicated six times (ones in each block) to estimate an error variance. Data on 13 quantitative characters were subjected to calculation of descriptive statistics, ANOVA and multivariate analysis (Unweighted Pair Group Method Analysis (UPGMA) cluster analysis and principal component analysis). There were significant differences (ANOVA, P<0.01) among landraces for plant height, 1000-seed weight, number of seeds per spike, days to heading and days to maturity. All the genotypes were grouped into five clusters where 74.02% of the accessions (433) fall in cluster I, IV and V. Early matured accessions were grouped in cluster I, while late matured, high yielding and tall accessions were clustered in cluster IV. The highest intra-cluster distance was 23.12 for 598

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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