Phenotypic Diversity and Variability of Common Bean (Phaseolus vulgaris L.) Landrace Germplasm from Ethiopia

Abstract

The Ethiopian genetic center is a secondary center of genetic diversity for the common bean. This study was conducted to determine the genetic diversity and variability among Ethiopian common bean landrace accessions, using agro-morphological phenotypic traits. A germplasm sample of 121 landrace accessions was developed, which represented different common bean production ecologies and seed types common in the country. Released varieties ‘Awash-1’ and ‘Melka-Dima’, were used as Mesoamerican and Andean control genotypes, respectively. The sample accessions were grown at the main research station of Melkassa Agricultural Research Center, Adama, Ethiopia, during the main rainy season of 2016. Data were collected on 18 agro-morphological traits, including 10 standard morphological descriptors. Results showed that sample germplasm showed broad variability ranges with respect to important distinguishing qualitative (morphological) character traits considered, such as seed weight, shape, color, etc. Similarly, significant variability among the accessions were observed for five yield-related traits and seed yield, indicating there was adequate variability vis-à-vis these traits in common bean accessions from different parts of Ethiopia. To this end, both Tocher’s and neighbor-joining clustering methods yielded five clusters from either of the two gene pools: Andean and Mesoamerican. D2 analysis showed the presence of significant inter-cluster distances. Finally, the first two principal component axes explained a substantial part of the variation (34%), with seven traits explaining most of the variation. This new information on phenotypic variability and genetic diversity improves our understanding of the organization of genetic diversity of Ethiopian common bean germplasm.

Keywords: germplasm, phenotypic, cluster analysis, PCA, inter-cluster distance, landrace