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Inheritance of Resistance to Aspergillus Ear Rot and Aflatoxin Production of Corn from Tex6

The inheritance of resistance to Aspergillus ear rot and aflatoxin production in corn (Zea mays L.) caused by Aspergillus flavus was studied in progeny derived from crosses between the resistant corn inbred cv. Tex6 and susceptible inbred cvs. B73 and Mo17. From 1994 to 1996, plant generations included were the P₁ (susceptible B73 or Mo17), P₂ (resistant Tex6), F₁, F₂, F₃, BCP₁, BCP₁-selfed, and BCP₂. The BCP₂-selfed generation was added in 1995 and 1996 for the B73 × Tex6 cross. Primary ears were pinboard inoculated and evaluated for Aspergillus ear rot severity. F₁ means deviated from the midparent value toward resistance for aflatoxin production and toward susceptibility for ear rot in both crosses. Analyses of generation means indicate that additive gene action was most important in the resistance to both ear rot and aflatoxin production in the B73 × Tex6 cross. Mo17 was somewhat resistant to both traits, so resistance from Tex6 was not well defined in this cross. Broad-sense heritabilities for ear rot and aflatoxin production were 58 and 63% for Mo17 × Tex6, and 66 and 65% for B73 × Tex6. Narrow-sense heritabilities for ear rot and aflatoxin production were 39 and 45% for B73 × Tex6. It is estimated that one cycle of selection for resistance within B73 × Tex6 F₃ families would reduce the percentage of ear rot severity by 8.5% and aflatoxin concentration by 19 ng/g.