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Efficiency of selection per se and in single-cross hybrids for disease resistance in maize

Author(s): R.B. Camargos, R.G. Von Pinho, M. Balestre, R.A.D.C. Ferreira, K.O.G. Dias, L.P.M. Pires and V.F. Souza

Plant breeding strategies are constantly refined to increase efficiency during the selection process. Consequently, the aims of this study were to examine genetic control and efficiency of selection based on the per se performance of maize lines and based on hybrid performance in reaction to white spot, common rust, and ear rot diseases in maize breeding programs. We also aimed to examine the relationship between the per se performance of the lines and the single hybrids for resistance to these diseases. To do so, we evaluated the reaction to these diseases in 106 lines and 661 hybrids in different locations in Brazil. Subsequently, the relative importance of the additive and non-additive genetic effects on expression of these traits, the association between the parameters considered upon carrying out the selection in these generations, and gain from selection were estimated. The results indicated that additive effects predominate for resistance to white spot and ear rot diseases, whereas for common rust, dominance effects predominate. However, evaluating the hybrids through diallel analysis was effective in selection for resistance to these diseases. The diseases and the generations evaluated were interrelated; the increase in the level of resistance had a more significant correlated response when selection was directed by the reaction to white spot, and there was a greater genetic similarity between the parameters considered in selection directed by hybrid performance.