Genotypic X Environmental Interaction of Cowpea Genotypes

Twenty four Cowpea varieties were raised at NIAB and ARRI, Faisalabad selected for plant height (42-136cm) days taken to 95 % flowering (62-79 days) and for diseases resistance (0.67-7 rating). Infestation was maximum on IT-97K-461-4, 1068-7, IT-97K 1042-8 and IT-98k-558-1 and was graded as susceptible. Maximum grain yield was recorded in Elite (649 kg/ha) and lowest grain yield was observed in IT-95K-1156-3 (332.3 kg/ha). Yield and yield contributing characters of twenty four entries tested revealed that they differ significantly from each other. The stability parameters for 12 locations indicated that the interaction was of cross over nature because the ranking of mean seed yield at 12 locations was dissimilar except NCP-1 which stood first at all the 12 locations. Regression coefficient of the six genotypes was non significant from zero. Standard deviation to regression S2d was also non significant except IT-97k-1042-8 genotype Elite with second highest yield performance had 0.982 non significant value of b near to unity and non significant S2d almost equal to zero (0.001). In addition to Elite the highest yielding line NCp-1 also showed stability because it had non significant regression coefficient (b) value from unity and non significant standard deviation to regression (S2d) from zero.