Genetic worth of multiple sets of cowpea breeding lines destined for advanced yield testing

The objective of this study was to determine genetic potentials in eight sets of cowpea lines for grain yield (GY), hundred seed weight (HSDWT) and days to 50% flowering (DT50FL). A total of 614 F₆ genotypes constituting the sets, grouped by maturity, were evaluated across two locations in Northern Nigeria, in an alpha lattice design, two replications each. Data were recorded on GY, HSDWT and DT50FL.Variance components, genotypic coefficient of variation (GCV), and genetic advance (G_A) were used to decode the magnitude of genetic variance within and among sets. Genetic usefulness (Up) which depends on mean and variance to score the genetic merits in historically bi-parental populations was applied to groups of breeding lines with mixed parentage. Principal component analysis (PCA) was used to depict contribution of traits to observed variations. GY and DT50FL explained the variance within and between sets respectively. Genotypes were significantly different, although genotype-by-location and set-by-location interaction effects were also prominent. Genetic variance (δ² _G) and GCV were high for GY in Prelim2 (δ² _G = 45,897; GCV = 19.58%), HSDWT in Prelim11 (δ² _G = 7.137; GCV = 17.07%) and DT50F in Prelim5 (δ² _G = 4.54; GCV = 4.4%). Heritability varied among sets for GY (H = 0.21 to 0.57), HSDWT (H = 0.76 to 0.93) and DT50FL (H = 0.20 to 0.81). G_A and percentage G_A (G_APM) were high for GY in Prelim2 (G_APM = 24.59%; G_A = 269.05Kg/ha), HSDWT in Prelim11 (G_APM = 28.54%; G_A = 4.47 g), and DT50F in Prelim10 (G_APM = 6.49%; G_A = 3.01 days). These sets also registered high values of genetic usefulness, suggesting potential application in non-full sib populations. These approaches can be used during preliminary performance tests to reinforce decisions in extracting promising lines and choose among defined groups of lines.

The online version contains supplementary material available at (10.1007/s10681-020-02763-y).