Heterosis and Combining Ability in a Diallel Cross in Sorghum vulgare Pers
1966
Niehaus, M. H. | Pickett, R. C.
Combining ability analyses were computed on a diallel cross of eight inbred sorghum lines in the F₁ and F₂ generations. Five of the lines were standard combine height grain sorghums and three were widely diverse and relatively recent introductions differing for height and maturity genes. The objective of the study was to determine the usefulness of recent sorghum introductions in a hybrid sorghum breeding program and to determine the yield components responsible for any heterosis obtained. Heterosis was striking, but only if at least one of the parents was an introduction. General combining ability effects were high in the F₁ and F₂ but specific combining ability effects were high only in the F₁. The correlation between the yield of the midparent and the yield of the F₁ (r = .07) indicated that the superior parents could not have been selected phenotypically. Number of seeds per head was the most important component of yield in the F₁ generation. From the available data it could not be ascertained whether the outstanding performance of the three introductions as parents was due to genetic diversity of many genes or to hybrid vigor associated with a relatively few height and maturity genes.
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