Exploring agro-morphological profiles of Phaseolus vulgaris germplasm shows manifest diversity and opportunities for genetic improvement

Common bean (Phaseolus vulgaris) is a seed crop with huge potential to contributing to food security in developing countries. In crop improvement, assessing genetic variability is a decisive step, requiring characterization of available crop germplasm. The present study aims at characterizing 39 common bean genotypes from various locations in Cameroon and five from Kenya using 19 qualitative and 36 quantitative traits of high descriptive values. Diversity among germplasm was assessed by determining diversity indices and carrying out multivariate analysis. Seventeen out of the nineteen qualitative traits (89.47%) were polymorphic, displaying each at least two phenotypic classes. High diversity was found. Average observed and expected number of phenotypic classes per trait were 3.74 and 2.53 respectively. Nei's genetic diversity value of 0.49 and Shannon-Weaver diversity index estimates of 0.74 were found. Significant differences were observed among genotypes for all measured quantitative traits. Yield traits showed significant correlation with other related quantitative traits. Cluster analysis separated the studied germplasm into three distinct groups, with the clustering pattern not showing any connection with location. The test of equality revealed significant difference between these clusters for most quantitative traits. Mahalanobis D2 statistics revealed germplasm of cluster I and III as potential parents for future breeding programs. This study identified genotypes with desirable agronomic traits such as higher number of seeds per pod, lower number of days to maturity, higher number of pods per plant, and higher yield. These and other important discriminatory traits are discussed and proposed for genetic improvement of common bean.