Resumo

BORGHI, ML et al. Combining ability of flint corn inbred lines: Mal de Río Cuarto disease tolerance and grain yield. Phyton (B. Aires) [online]. 2012, vol.81, n.1, pp.123-131. ISSN 1851-5657.

Mal de Río Cuarto (MRC) disease is a significant threat to corn production in Argentina. Sixty six hybrid combinations derived from the cross of twelve flint maize (Zea mays L) inbred lines were evaluated using a completely randomized block design with two replications. MRC disease severity grade (SG) and grain yield (GY) were the analyzed traits. Our objectives were to estimate the general (GCA) and specific (SCA) combining abilities for these traits among twelve corn inbred lines, and to identify potential heterotic relationships among them. Diallel crosses were performed and these results were compared using Griffing's method 2 model I and diallel GGE biplot (genotype main effect plus genotype x environment interaction). Highly significant effects for GCA and SCA for SG were observed, suggesting that both additive and non-additive genetic effects contribute to MRC tolerance. At the same time, GY showed significant effects only for SCA, hence non additive genetic effects are more important determinants of grain yield. Using both analysis methodologies, lines with good GCA to MRC tolerance and also heterotic crosses for this trait and GY were identified. These promising new crosses need further evaluation to assess their agronomic performance in larger field trials and establish whether they remain heterotic throughout an array of different productive environments, before they are included in future breeding efforts.

Palavras-chave : Zea mays L; Diallel crosses; GGE biplot; Combining ability.

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