Diallel analysis of cowpea (Vigna unguiculata (L.) Walp.) for some physical properties of seed under the Sudano-guinean conditions

Abstract

The present study was undertaken at Dang (soudano-guinean zone of Cameroon) to determine the variability of 100-seed weight, geometric surface, porosity and sphericity of the seeds of 10 cowpea (Vigna unguiculata) genotypes and investigate the genetic basis of these characters through a 5x5 half-diallel cross mating. Knowledge of the physical properties of the seed of cowpea was necessary for the design of equipment for transporting, sorting, cleaning, separating, smashing and processing it into different foods. The experimental design was a randomized complete block with three replicates. Analysis of results showed that these genotypes presented a significant variability for the four physical properties. The average properties of seed were found to be a hundred seed mass of 20.46g, a surface area of 0.84 cm2, a sphericity of 35.50% and a porosity of 0.65. Genetic analysis demonstrated that the parents differed for their general combining ability (GCA) and the crosses showed specific combining ability (SCA). These physical parameters were highly heritable with broad-sense heritability (h2) values ranged from 0.76 to 0.96 suggesting that genetic advance was expected. Both dominant and additive gene effects were significant for all traits with a predominance of additive genes for seed mass and dominant genes for degree of sphericity. The alleles for seed weight, degree of porosity and sphericity were mostly recessive whereas the higher performances for seed surface where due to the presence of dominant alleles. Heterosis in F1 over best parent was recorded for some combinations. For these traits, recurrent selection might be a useful breeding strategy.