FIELD AFLATOXIN CONTAMINATION OF MAIZE GENOTYPES OF BROAD GENETIC BASE

Contamination of maize (Zea mays L.) grain prior to harvest with aflatoxin frequently occurs in the southern U.S.A. and sources of resistance are needed. Maize from twelve genotypes (varieties) crossed to two testers was analyzed for aflatoxin B1 (AFB1) contamination at Baton Rouge, LA and Tifton, GA in 1987. Variety Philippines had the lowest amount of AFB1 at Baton Rouge and one of the lowest amount of AFB1 at Tifton. In the combined analysis of variance, the location X treatment X tester X variety interaction was significant. This interaction was analyzed and a stability variance (sigma-i2) statistic calculated. Mean AFB1 accumulation and stability of AFB1 production were examined simultaneously, i.e., variety ranks for AFB1 and sigma-i2 were summed. The most desirable (lowest rank sum) variety across locations, testers, and treatments (inoculation and control) was St. Charles White, followed by Delta Prolific White, and Hopi. The most inconsistent AFB1 accumulation, along with high AFB1, was on Fino, Atkinson, USAWI, Navajo, and Michoacan-21. The ranks of varities between the inoculation and control treatments were different (r(s) = -0.51 for Baton Rouge and 0.29 for Tifton). The r(s) (rank correlation coefficient) for the control treatments between Baton Rouge and Tifton was 0.60 (P < 0.05) and that for the inoculation treatments was -0.20. The varieties identified in this study as having relatively low concentration of AFB1 should be useful to maize breeders in reducing AFB1 contamination in field maize.