Variability and Heterosis in Cowpea (Vigna Unguiculata (L ) Walp. ) Accessions from Four Regions of Ghana

Abstract

Forty-five cowpea accessions, randomly selected from cowpea germplasm from four cowpea-growing regions of Ghana, namely, Upper East, Upper West, Northern and Eastern Regions, were characterized and evaluated at the Plant Genetic Resources Unit of the Crops Research Institute at Bunso with the objective to determine the range of variability in the samples with respect to vegetative, inflorescence and fruit characters. The variability in the samples was used to initiate hybridization among some selected accessions from the collection. Subsequently heterosis was determined for flowering and maturity dates and yield and yield components in four crosses among the selected accessions with the view to improving the yield. Large variability was observed in most of the qualitative characters, particularly growth habit, twining tendency, plant and pod pigmentation, raceme position, pod attachment to peduncle and flower colour of the germplasm. The accessions differed significantly in their days to flowering and maturity, peduncle length, number of peduncles per plant, number of pods per plant, pod length, number of seeds per plant, 100-se.ed weight and grain yield per plant. There were also significant between- aod withinregion differences I'n these characters. t Heterosis for pods per plant .and grain yield per plant in all the four crosses was positive and high. This was particularly so for grain yield per plant for the cross between accessions 87/27 and 87/157 in which heterosis was about 130%. The possibility of using accessions 87/27 and 87/157 for future improvement programmes of the crop is discussed based on their performance in this work.