Avanços na ciência e tecnologia agrícola

Abstrato

Estimates of Combining Abilities and Components of Variances of Tropical Maize Genotypes under Northern Leaf Blight Disease Infection

Akinlolu O. Ohunakin

Northern Leaf Blight (NLB) disease is among the most devastating disease of maize worldwide contributing about 50% yield losses annually. 45 single cross hybrids generated through half diallel from ten tropical maize (Zea mays L.) inbreds including their ten parents and one hybrid check were evaluated at five environments using 9 × 7 alpha lattice designs with three replications across five environments to determine their combining abilities and genetic variance components. The significant mean squares detected for environment, genotype, and Genotype × Environment (G × E) for measured traits revealed uniqueness of the test environments, and adequate genetic variability among the inbred lines to allow good progress from selection for improvements in most of the measured traits. Significant effects of GCA and SCA expressed for all traits across environments indicated the participation of both additive and non-additive gene effects in the inheritance of the traits. The greater proportion of General Combining Ability (GCA) effects over Specific Combining Ability (SCA) effects across environments suggested that additive gene played a dominant role in the inheritance of the studied traits in the single cross hybrids evaluated. This indicated that additive gene action was more important than the non-additive gene effects in modulating the inheritance of the measured traits associated with NLB disease resistance. Higher GCA variance expressed by grain yield, NLB score and ear weight shows the preponderance of additive gene actions in controlling the inheritance of these traits, thus, indicates the importance of additive gene effects than non-additive gene effects in the expression of these traits. Higher significant relationship revealed between the characters for genotypic correlation over phenotypic correlation indicates a less influence of the environment on the characters.