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This article in CS

  1. Vol. 11 No. 2, p. 180-184
    Received: May 6, 1970

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Gene Action Conditioning Resistance to Northern Leaf Blight in Maize1

  1. G. R. Hughes and
  2. A. L. Hooker2



The nature of gene action conditioning the quantitative type of resistance in maize (Zea mays L.) to Northern leaf blight caused by Helminthosporium turcicum Pass. was studied in crosses between four Australian resistant inbred lines (D21, HB, 21H, and 25) and three tester inbred lines (susceptibles H10 and 701, and moderately resistant Oh43). Populations composed of the P1, P2, F1, F2, BC1P1 and BC1P2 generations were studied for the 12 possible crosses in 1966 and with the addition of F3, BC1P1S and BC1P2S families for four crosses in 1967.

Additive, dominance, and epistatic gene action were detected by analysis of generation means. Additive gene action was of major importance in all crosses in both years. The relative importance of non-additive effects was generally small and varied with the population involved and, to a lesser extent, with the year of study. Although biased by limitations in experimental and analytical design, estimates of components of genetic variance were in general agreement with the results of the generation mean analysis.

It was concluded that leaf blight resistance in these lines was conditioned by a relatively low number of genes, primarily additive in effect. Breeding for resistance to this disease should be effectively accomplished by such simple procedures as phenotypic recurrent selection or mass selection.

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