Assessment of Diversity in Cowpea (Vigna unguiculata (L.) Walp.) Cultivars Using Agromorphological Traits

Abstract

In Chad, cowpea is a second cash crop leguminous after groundnut but the local varieties are not valorized. The aim of this study was to evaluate the agromorphological variability of forty-five cultivars and its structuring based on eighteen descriptors. The main cultivated cowpea seeds have kidney shaped (84.44%), white (73.33%) with thin and rough integument (91.11%). The pods are also white but not dehiscent. Highly significant differences were observed for seven quantitative traits. Principal component analysis explained 73.04% of the variability. Discriminant Factor analysis confirmed 97.78% of the classifications resulting from the hierarchical ascendant clustering. Cultivars are structured into 4 groups characterized by seed weight per pod, pod length, pod weight per plant and maturity stage. Group I, is characterized by late cultivars (Fl1: 87±2.42 days; Mat: 108±1.80 days) with short pods (PoL: 13.92±0.63 cm). Group II cultivars, had the highest pod weights (PoWP: 129.69±6.81 g) and seed weights per pod (SWPo: 3.98±0.09 g). Group III includes cultivars with intermediate traits. Group IV cultivars are the earliest (Mat: 65±2.71 days) with long pods (PoL: 21.05±0.94 cm). The interesting cultivars and traits will be used to improve cowpea productivity.