Irrigation, Planting Date, and Corn (Zea mays L.) Hybrid Selection Impacts on Aflatoxin Accumulation.

Aflatoxin poses a threat to the food supply by potentially contaminating corn by the production of the fungi Aspergillus flavus. In this study, Aspergillus flavus was inoculated into commercially available corn (Zea mays L.) hybrids and were subject to various cultural practices such as irrigation and planting date. The objective of this research was to determine the effects of delayed irrigation trigger, planting earlier, and drought-tolerant and short-season hybrids on aflatoxin accumulation. Trials took place at Mississippi State, MS and Verona, MS in 2016 and 2017. Treatments were randomly assigned in a split-split plot arrangement. Irrigation events applied to each field were monitored with flowmeters, and timings were initiated based on two soil moisture sensor triggers, -50kPa and -125kPa. Two planting dates, 30 days apart, within the corn-planting window in each location were utilized. Selected germplasm includes drought-tolerant, short-season and full-season hybrids. In result, when inoculated, hybrid type (P = 0.02) and the interaction between year and planting date (P = < 0.01) affect aflatoxin accumulation but irrigation threshold (P = 0.70) does not. Also, when not inoculated, year (P = < 0.01) and the interaction between planting date and hybrid affect aflatoxin accumulation but irrigation threshold (P = 0.89) does not. Inoculated drought-tolerant and short-season hybrids accumulated 8% greater aflatoxin levels compared to the full-season hybrids. Inoculated hybrids planted earlier in 2016 had 17% greater aflatoxin levels than later planted corn, while in 2017, there was no effect due to planting date. When hybrids were non-inoculated, planting earlier with short-season and full-season hybrids generated lesser aflatoxin levels. This data suggests that yearly environmental conditions such as above average temperatures and less than average rainfall can affect aflatoxin. Whether inoculated or non-inoculated, using the standard full-season hybrids reduced the accumulation of aflatoxin.