Assessment of Genetic Diversity of Bambara Groundnut Accessions [Vigna subterranea (L) Verdcourt] in Sahelian Zone of Niger

Abstract

The agro-morphological characterization of plant genetic resources is crucial to understand the phenotypic and genotypic relationships between different crop varieties. Bambara groundnut (Vigna subterranea) is a grain legume grown worldwide due to its high nutritional values, nitrogen-fixing ability, and drought tolerance. To assess the existing genotypic and phenotypic diversity within Bambara groundnut accessions and to estimate the genetic parameters guiding future varietal improvement programs, 22 Bambara groundnut accessions were characterized in the Sahelian zone of Niger. Thus, the coefficient of variation ranged from 2.42% to 48.25%, and 7 of the 22 parameters measured presented high coefficients of variation (CV˃20%). Yield had positive high correlation with shell weight (r=0.56), 100-seed weight (r=0.61), and seed weight (r=0.99). The highest GCV and PCV were observed in number of seeds per plant (PVC=35.05% and GCV=22.65%), hull weight (PVC=85.91% and GCV=25.51%) and dry biomass weight (PVC=36. 61% and GCV=23.66%), for a respective heritability and genetic gain of: (h2b=41.58%; GA=30.03%), (h2b=8.82%; GA=15.60%) and (h2b=41.76%; GA=31.49%). The highest heritability is observed in the number of leaves (92.40%) and the date of maturity (92.08%). Emergence date revealed high heritability and genetic gain (h2b=78.77% and GA=20%). Parameters with high heritability and genetic gain (h2b≥60% and GA≥20%), are the least influenced by the environment. So, direct selection for improvement of these traits may be beneficial. To authenticate genetic inequality, principal component analysis (PCA) and hierarchical ascending clustering (HAC) were performed. The results showed a great agro-morphological diversity divided into four different groups, for the studied characters. Group 3 (4 accessions) and group 1 (3 accessions) are the high yielding accessions, while group 4 (8 accessions) and group 2 (7 accessions) are the lower yielding accessions. ...................