Estimates of General and Specific Combining Ability in F₁ Hybrids for Grain Yield and Its Components in Grain Sorghum, Sorghum vulgare Pers.¹

Abstract

The performance of 40 F1 hybrid populations of grain sorghum, obtained by crossing each of 5 male‐sterile lines to 8 pollen‐fertility restoring lines, was evaluated from tests conducted at 3 locations over a 2‐year period. Measurements for grain yield, number of heads per plant, weight of 100 seeds, and number of seeds per head were analyzed to obtain estimates of the relative magnitude of general and specific combining effects. Significant differences among general combining ability effects of the lines were obtained for all characters, while significant differences among specific combining ability effects were expressed only for 100‐seed weight. An evaluation of variance components revealed that the variances for general combining ability for grain yield were three times larger than the component for specific effects. A similar ratio for the two effects was obtained for both number of heads per plant and weight of 100 seeds. For number of seeds per head, the ratio of general to specific effects was markedly larger than the ratio observed for the other characters. Specific combining ability effects were usually more stable than general effects over the environments of this experiment, particularly for grain yield and seeds per head.Correlations for the association of grain yield with its components disclosed that number of seeds per head was the component most highly related to yield, and that the expressions for yield were not affected appreciably by 100‐seed weight. While the ranges observed for number of heads per plant were relatively small in this experiment, significant negative associations for this trait with grain yield were observed for both the hybrids and parental lines.

Combining ability and heterotic pattern in West African sorghum landraces

“…These results were in agreement with findings of Kenga et al (2004) reporting on prevalence of non-additive variance for days to anthesis, plant height, inflorescence length and grain yield per plant. Contrary to our study, earlier works have reported that additive gene effects were a predominant factor determining grain yield in sorghum (Beil and Atkins, 1967;Kirby and Atkins, 1968). The previous studies used breeding lines or previously characterized genotypes with known behaviour in cross.…”

Diallel analysis of cassava brown streak disease, yield and yield related characteristics in Mozambique

“…Analysis of general (GCA) and specific (SCA) combining ability for individual experiments was performed, and mean squares of GCA and SCA were used to determine GCA:SCA ratios (Beil and Atkins 1967;Haussmann et al 1999). …”

Heterosis for yield and related characters in pea

“…The GCA of any male line was estimated as the deviation of the mean performance of its F1 hybrids with all female parents from the grand mean, and the GCA of any female line was calculated correspondingly. The male × female interaction effect was used to estimate SCA (Beil & Atkins, 1967) although the experimental design did not allow the separation of true SCA from maternal or reciprocal effects, which tend to be small in this species (Gritton, 1975;Samad et al, 1989). The levels of heterosis over the mid-parent or parental average, heterosis over the better parent, superiority over the best parent and inbreeding depression from F1 to F2 were calculated:…”