Genetic Variability, Correlation and Path Coefficient Analysis in Seed Yield and Related Traits of Cowpea (Vigna Unguiculata (L.)Walp) Germplasm Accessions on High Altitude Area of Jos Plateau

Abstract

A field experiment was carried out at Dagwom farm at National Veterinary Research Institute (NVRI) Vom, in Jos South Local Government area of Plateau state Nigeria (Lat.09044N, long.08047E, altitude 1293.2 m above sea level) in 2013 and 2014 rainy seasons, to evaluate the genetic variability, correlation and path coefficient analysis in seed yield and related traits of cowpea. The treatments consisted of eighty (80) cowpea germplasm accessions obtained from International Institute for Tropical Agriculture (IITA) Ibadan Nigeria. The experiment was laid out in a Randomized Complete Block Design (RCBD) in two replicates. The Analysis of Variance (ANOVA) showed significant difference at (P<0.01) among the entries for all the yield and related traits accessed. High phenotypic coefficient of variability (PCV) compared with genotypic coefficient of variability (GCV) coupled with low Environmental coefficient of variability (ECV) was observed for all the yield and related traits accessed. High broad sense heritability (H2B) and genetic advance (GAM (%) was observed for the entire yield and related traits accessed except days to maturity which recorded high heritability with moderate genetic advance. Significant positive correlation was observed between grain yield and number of pod per plant (r=0.572**), hundred seed weight (r=0.504**), pod length (r=0.523**), number of secondary branches per plant (r=0.450**), number of seed per pod (r=0.431**), number of primary branches per plant (r=0.339**) plant height (r=0.285*), suggests that improving any of these characters will boost grain yield of cowpea. Path coefficient analysis showed that, number of pod per plant (P=0.65), hundred seed weight (P=0.54), number of seed per pod ((P=0.29) number of secondary branches per plant ((P=0.16), plant height (P=0.05)), and pod length ((P=0.04) contributed directly to grain yield. The result from this study therefore revealed that hundred seed weight, number of pod per plant, number of secondary branches per plant, number of seed per pod, pod length and plant height recorded high genetic variability, heritability and genetic advance coupled with high significant genotypic correlation with grain yield and contributed directly to grain yield. Therefore, these characters should be considered when planning hybridization programme for cowpea yield improvement.