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Inheritance of resistance to stalk rot, caused by Colletotrichum graminicola (Ces.) wils, in maize (Zea mays L.)

Oswaldo A.P. Pereira^I; Eric Balmer^II; José B. Miranda Filho^II

^ISementes Agroceres S.A., Jacarezinho, PR, Brasil
^IIDepartamento de Genética, ESALQ/USP, Caixa Postal 83, 13400 Piracicaba, SP, Brasil. Send correspondence to J.B.M.F.

ABSTRACT

Six inbred lines of maize (Zea mays L.) were crossed in a diallel mating scheme, and the 15 crosses were designated as families. Each family was represented by six generations: parents (P1 and P₂), F₁, F₂, and backcrosses (B₁ and B₂). Significant differences were detected among families and among generations within families for the percentage of the stalk area affected by the causal pathogen (Colletotrichum graminicola).The generation mean analysis showed that additive effects were significant in most families. Only two families had nonsignificant additive effects, while five out of 15 families had nonsignificant dominance deviations. The direction of dominance was not consistent among crosses but indicated a tendency of heterosis toward higher susceptibility. Deviations from the genetic-statistical model were not significant in most crosses, thus showing the effectiveness of the model for explaining the variation of generations in relation to the resistance level. It was concluded that the relative importance of additive and dominance effects depends on the particular cross under study, although both effects may prove to be important sources of variation.

Keywords: resistance; Colletotrichum graminicola; maize; Zea mays.

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