Quantification of Aspergillus flavus Growth on Inoculated Excised Kernels of Corn Genotypes1

Abstract

abstractCorn (Zea mays L.) genotypes that resist invasion by Aspergillus flavusor inhibit toxin production would be one major approach to controlling aflatoxin contamination. The primary objective of this study was to determine if a particular laboratory technique could be used to detect differences in responses to A. flavusgrowth among maize genotypes. In addition, several other aspects were considered including a) effect of pollen source, b) kernel sample size, c) incubation period, d) surface sterilization of kernels, and e) stage of kernel development when sampled. Evaluation of corn genotypes involved the removal of kernels from ears of field‐grown hybrids at various times throughout the kernel development period. Kernels were placed on NaCl amended agar in petri dishes and inoculated with a suspension of A. flavusconidia. After incubation, samples were evaluated by recording the extent of A. flavusgrowth on each kernel. Significant genotypic differences were detected at all stages of kernel development sampled. However, these differences were not always consistent over sampling dates nor were they always consistent over years for a given sample date. Visual ratings of kernels sampled early in the kernel development period were higher than the ratings of those kernels sampled toward the end of the maturation process. Surface sterilized kernels promoted more A. flavusgrowth than did unsterilized kernels. Evaluation of F1, seed produced on inbreds revealed significant differences between reciprocal crosses. When a resistant inbred was used as the female parent, the seed gave a resistant response. However, when the susceptible parent was used as a female, A. flavusgrowth on inoculated kernels was markedly greater.