Diversification of cowpea in the Mediterranean and other centres of cultivation

A collection of cowpea (376 accessions) together with two lesser collections of asparagus bean (cv-gr sesquipedalis, 22 accessions) and catjang bean (cv-gr biflora, 35 accessions) from 19 countries of origin, were characterized and evaluated for studying their genetic variability and diversification in relation to geographical provenances: this aim was reached using both techniques of univariate and multivariate analysis (hierarchical analysis of variance, discriminant analysis of canonical variables and cluster analysis). The results show clearly: a) the grouping of the origins in three main clusters; b) that the cowpea from the USA is more similar to the Mediterranean cowpea than to the African one; c) cowpea from centre of origin presented a shorter and broader pod, almost the same number of locules and a lower seed weight in comparison with other provenances: d) on the average the cowpea from south-central Africa was the least variable, while the Mediterranean one recorded the most variable indicating a greater variability in this region of cultivation; e) a high positive correlation (r = 0.9) between flowering time and ripening time in all cv-grs, and that peduncle length is never correlated with other traits; f) a low mutual relation between genetic and geographical difference; g) cv-grs were significantly different from one another in individual regions for almost all the descriptors.