Grain yield and stability of selected early and medium duration cowpea in Ghana

Changes in climate are a major driver for climate-smart crops with short duration on-field and adaptation to diverse growing conditions. This study evaluated the performance of nine early duration and 10 medium duration cowpea genotypes at six locations within the Guinea and Sudan savanna zones of Ghana. Genotypes for each maturity group were laid out in a Randomized Complete Block Design with three replications for each location. There were significant (p<0.001) genotype, environment and genotype x environment effects of the cowpea genotypes of both maturity groups for grain yield. Among the early duration cowpea tested, GGE biplot analysis revealed SARI-2-50-80, SARI-13-17-2, IT99K-1122, SARI-3-11-80, and IT07K-299-6, respectively, as having high yield and stable performance across the six test environments; and out-performed the check variety, Kirkhouse Benga. With the medium duration trials, IT86D-610, IT10K-837-1, and SARI-6-2-6 had high yields, which were comparable to the check, Padituya. IT10K-837-1 was the most stable and had a relatively shorter maturity period.  Grain yield performance of early duration cowpea was discriminated by three mega environments while only two mega environments discriminated grain yield of medium duration cowpea. The selected genotypes could be used in hybridizations or released as cowpea varieties in the country.   Key words: Genotype x environment, maturity period, multi-location, biplot analysis, genetic variability.