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Resistance

The Inheritance of Resistance in Corn to Cochliobolus carbonum Race 3. A. H. Hamid, Graduate student, Department of Plant Pathology, USDA, ARS, The Pennsylvania State University, University Park 16802, Present address: Malaysian Agricultural Research and Development Institute (MARDI), Serdang, Selangor, Malaysia; J. E. Ayers(2), and R. R. Hill, Jr.(3). (2)Professor, Department of Plant Pathology, USDA, ARS, The Pennsylvania State University, University Park 16802; (3)Research agronomist, Regional Pasture Research Laboratory, USDA, ARS, The Pennsylvania State University, University Park 16802. Phytopathology 72:1173-1177. Accepted for publication 21 January 1982. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982.. DOI: 10.1094/Phyto-72-1173.

Diallel cross analyses were used to study the nature of gene action governing resistance in corn (Zea mays) to an isolate of Cochliobolus carbonum (=Helminthosporium carbonum) race 3. Disease efficiency, lesion length, and sporulation capacity were used as resistance parameters when seedlings were screened for resistance in growth chamber studies while lesion length only was used in field studies. A total of 134 F₁ and selfed inbred parents were tested for resistance against a virulent isolate of the fungus. Additive gene action was much more important than nonadditive gene action in controlling resistance for all the three traits used in the study. Average heterosis, line heterosis, specific combining ability effects, and maternal effects were occasionally significant, but were always much smaller than the additive effects.