Numerical and RAPD Analysis of Eight Cowpea Genotypes from Nigeria

Abstract

Cowpea, Vigna unguiculata (L.) Walp is one of the world’s main legumes and is an important source of plant protein in human diet as well as a good cover crop. The wealth of any germplasm is measured in terms of the genetic variability. Hence, numerical tools such as single linkage cluster analysis (SLCA) and principal component analysis (PCA) have been used to determine the extent of variability. This study was conducted to determine the performance, character contribution as well as variation pattern in eight cowpea genotypes collected in Nigeria. Field evaluations were carried out in June and September, 2015 and also molecular studies. Data collected were subjected to analysis of variance and Duncan’s multiple range test was used to separate significant means at 5% probability level. Molecular data were subjected to NTSYS-pc software. Genotype IT98K-573-1-1 had the highest 100-seed weight (26.06g) and seed weight per plant (36.00g). The first three PCA had eigen values greater than one and accounted for 75.48% cumulative variance. Pod length, 100-seed weight and seed weight per plant contributed significantly to the overall variation observed in the genotypes. The agro-morphological and molecular dendrograms grouped the genotypes into four and three groups, respectively with genotype IT98K- 73-1- 1 clearly distinguished by the molecular dendrogram. Knowledge of the character contribution as well as variation pattern will assist plant breeders in the choice of parents for hybridization in future breeding programmes.

Key words: cowpea, genotype, dendrogram, PCA, SLCA