INHERITANCE OF RESISTANCE TO ASPERGILLUS EAR ROT AND AFLATOXIN IN CORN GENOTYPES

The inheritance of resistance to Aspergillus ear rot of corn (Zea mays ) caused by Aspergillus flavus was studied in progeny derived from cro sses between resistant (LB31, L317, CI2, N6, 75-R001, B37Ht2, OH513, T ex6, and H103) and susceptible (B73 and/or Mo17) inbreds following ino culation. In 1992 and 1993 the parental, F-1, F-2, F-3, and both backc ross generations of 11 crosses were tested. The number of generations evaluated for each cross was dependent on the year. Parental and F-1 g enerations, as well as five F-2 and three F-3 populations, were evalua ted for aflatoxin content in 1992 and 1993. Generation mean analysis i ndicated additive and dominance gene action were of primary importance in resistance to Aspergillus ear rot. Dominance genetic effects estim ates ranged from 0.0 to 87.3% of the variation between generation mean s. Inbreds TexB, LB31, CI2, and OH513 consistently had the highest lev els of resistance. Frequency distributions of aflatoxin content of ear s on F-2 plants and ears on F-3 families (lines) of the Mo17 x Tex6 an d B73 x LB31 populations were highly skewed toward the resistant paren t, indicative of genic dominance. The F-2 and F-3 generations indicate d various levels of transgressive segregation for resistance to Asperg illus ear rot and to aflatoxin production.