Genetic evaluation of cowpea (Vigna unguiculata (L.) Walp.) using morphological characters

Abstract

The experiment was conducted to characterize cowpea (Vigna unguiculata (L.) genotypes based on morphological characters. The experiment was carried out at the screen house of the Institute of Agricultural Research and Training (IAR&T), Moor Plantation, Ibadan in 2015 and 2016 using nine (9) cowpea varieties. Soil was sieved with 2mm sieved and sterilized. The experiment was laid out in Completely Randomized Design (CRD) with four replicates. Morphological data were collected based on descriptor for cowpea (IBPGR, 1983). For quantitative traits, analysis of variance revealed that genotype and years effect mean squares from pooled data were highly significantly different for days to first and 50% flowering (P ˂ 0.01), interaction between genotype and years effect also had significant effect on days to first and days to 50% flowering (P ˂ 0.05).Higher significant values were obtained for terminal leaf width, pod weight, pod length, days to physiological maturity, total seed weight per plant, 100 seed weight and number of seed per plant in 2015 than the year 2016. However there were no significant differences obtained for terminal leaf length, pod per peduncle, number of pod per plant, seed length, seed width, seed thickness, and number of seed per pod in both years. Qualitative characters results show thatgenotypic effect, year effect and their interactions were not significant for plant vigour. Modupe, Ife 98-12, Oloyin-Pelebe, Ife BPC, Oloyin-Nla and Sokoto genotypes had intermediate twining tendency. Drum and Mulla had pronounced twining tendency while Ife Brown had no twining tendency. Based on pooled cluster analysis the dendrogram grouped the varieties in two different major clusters A and B. Cluster A comprised of seven genotypes; Oloyin-Nla, Oloyin-Pelebe, Sokoto, Ife BPC, Modupe, Ife 98-12 and Ife Brown. Cluster B comprised of two genotypes; Drum and Mulla. This implies that genotypes within the same cluster had similar genetic background, while genotypes in cluster A are distant on the chromosome as compare to genotypes on cluster B respectively.

Keywords: Genetic evaluation, Vigna unguiculata, Cowpea, Morphological Characters