Progress in genetic improvement for grain yield potential and associated traits of cowpea (Vigna unguiculata L. Walp.) and genotype environment interactions in the INERA cowpea breeding programme

Abstract

The INERA cowpea breeding programme, established in 1978, has made significant progress in developing high yielding, pest resistant and farmer preferred varieties of cowpea (Vigna unguiculata L. Walp.). Despite the advances made by the INERA cowpea breeding programme, the genetic progress on yield and grain quality achieved so far has not been estimated. Evaluating this genetic progress is crucial to understanding the effectiveness of the breeding efforts to guide future improvements. The objective of this study was to establish a scientific basis for the progress of the breeding programme in terms of grain yield and associated traits through a genotype environment (GxE) study. Trials with 30 cowpea genotypes were conducted at five locations during the rainy seasons of two consecutive years, 2017 and 2018, spanning from July to October. The experimental design was a 6x5 alpha lattice replicated three times at each location for both years. Highly significant differences were observed between both genotypes and environments for variables days to 95% maturity, 100 seed weight and grain yield, indicating the presence of genetic variability among genotypes for these traits. The GGE biplot analysis identified two mega environments for days to maturity and seed weight. In contrast, for grain yield, three mega-environments were constituted. Genotypes Tiligre and Gourgou were identified as the best performing and most stable across environments for seed size. Genotypes Tiligre and KVx396-4-5-2D were the most stable in terms of yield performance. Tiligre combined good stability for seed size and high yielding, and as such can be refered as an elite genotype. The genotype Komcalle, is less stable as compared to Tiligre, but possesses farmer preferred traits such as short maturing cycle and good seed quality. Tiligre and Komcalle reflect the important genetic progress achieved in terms of yield performance, required seed characterictics, and short duratoin cycle. They are currently the most preferred and largest cultivated varietes in Burkina Faso.