One hundred cowpea (Vigna unguiculata L. Walp) accessions comprising 21 improved varieties and 79 landraces obtained from the Genetic Resources Center of the International Institute of Tropical Agriculture (IITA), Ibadan, were evaluated to assess morphological diversity and identify early-maturing, high-yielding accessions based on seedling emergence, flower and pod appearance, number of pods harvested and the number of seeds harvested per plant for crop improvement. The experiment was conducted in a screenhouse using a completely randomized design with three replications. Qualitative traits were analyzed using frequency distribution while quantitative traits were subjected to analysis of variance (ANOVA) followed by mean separation using least significant difference (LSD, α = 0.05). Cluster analysis was performed based on seedling emergence, morphological and reproductive traits. Results showed substantial variability among accessions with predominance of brown seed coat colour (45%), globular seed shape (63%), smooth seed coat texture (73%), white flowers (48%), erect growth habit (83%), and non-twining type (93%). Significant differences were recorded for days to emergence, flowering, and podding. Accessions TVu-1497, TVu-10303, and TVu-11545 emerged earliest; TVu-1702, TVu-1544, and TVu-3000 flowered earliest; while TVu-3657, TVu-3000, and TVu-2252 reached podding earliest. TVu-3658, TVu-1387, and TVu-1707 combined earliness with superior yield performance, whereas TVNu-1963, TVu-14040, and IT98K-205-8 failed to flower. Cluster analysis grouped the accessions into three major clusters, revealing useful genetic diversity for breeding programmes. Twelve accessions combining desirable morphological traits, early maturity, and yield potential were identified as promising parental lines for the development of improved cowpea varieties.

Keywords: Genetic diversity, morphological traits, earliness, cluster analysis, breeding programme.