Gene action and combining ability studies for grain yield and its related traits in cowpea (Vigna unguiculata)

Abstract

Identification of superior genotypes from variability generated via hybridization and understanding the nature of the gene action controlling grain yield and related traits are crucial for cowpea varietal improvement. A field experiment was conducted at the Savannah Agricultural Research Institute, Tamale-Ghana in the 2016 cropping season to examine the combining ability, genotypic and phenotypic correlations for grain yield and other agronomic characters in 25 cowpea genotypes (5 parents and 20 hybrids derived from a diallel cross of the parents). The result indicated that the general combining ability and specific combining ability varied for all characters measured signifying the prominence of both additive and non-additive genetic components in the present study. Non-additive gene action was important for grain yield, canopy width at maturity, plant height (PLHTF), number of seeds per pod, pod weight and days to 50% flowering (DFF). On the other hand, additive gene action was important for days to maturity (DM) and pod length. Parents PADI-TUYA and IT86D-610 were observed to be good general combiners for grain yield and other traits while IT86D-610 × PADI-TUYA, SONGOTRA × PADI-TUYA and IT86D-610 × SARC 57–2 were identified as promising specific combiners for grain yield and related traits. Selection criteria to improve the grain yield of cowpea should focus on plants with long peduncles, high canopy width and many pods per plant as these traits have high genetic correlation with grain yield.

Keywords

• diallel mating design
• heterosis
• genotypic correlation
• vigna unguiculata