Variability, seasonal effects and principal component analysis of cowpea (Vigna unguiculata) genotypes in Uyo, Nigeria

Abstract

Field experiments were conducted in 2017 early and late cropping seasons at National Cereals Research Institute, Uyo Out Station, Owot Uta, Ibesikpo Asutan LGA of Akwa Ibom State to determine variability, seasonal effects and principal components of growth characters, yield and yield components of seven cowpea genotypes. The experiments were laid out in a randomized complete block design in four replications. Fourteen characters were studied namely; percentage establishment (%), plant height (cm), number of leaves, leaf area (cm2), number of branches per plant, days to first flowering, days to 50% flowering, length of pods (cm), girth of pods (cm), number of pods per plant, number of seeds per pod, weight of pods (g), weight of 100 seeds (g) and seed yield (kg/ha). Significant differences (p<0.05) were observed among the cowpea genotypes in plant height, number of leaves, number of branches per plant, number of pods per plant, number of seeds per pod and seed yield (kg/ha). The cowpea genotypes IT89KD391B was superior in 5 characters, namely plants heights (cm), number of leaves, leaf area (cm2), length of pods (cm), girth of pods and weight of 100 seeds, followed by Ife brown for days to first flowering, days to 50% flowering, number of pods per plant, number of seeds per pod and seed yield (kg/ha) while IT89KD260 recorded the highest percentage establishment and number of branches per plant. First 4PC with Eigen values greater than 1.0 jointly explained 89.3% of the total variations in the genotypes. Significant seasonal effects were observed on plant height, number of leaves, number of branches, number of pods, number of seeds per pod, and seed yield (kg/ha). The result identified late cropping season as the best season for cowpea production in Uyo, Southern Nigeria.