Effect of grain coverage disruption on aflatoxins in maize and sorghum

Aflatoxins are dangerous mycotoxins in crop production, demonstrated to reduce crop quality and value through both pre- and post-harvest contamination. Aflatoxin contamination is encountered much more frequently in maize (Zea mays L.) than its close relative sorghum [Sorghum bicolor (L.) Moench]. This study focused on evaluating the effect of grain coverage on aflatoxin accumulation in both crops; comparing coverage of the female inflorescence (exposed sorghum grain vs. husk covered maize grain) as well as the impact of paper bag coverage during pollination activities. The maize and sorghum female inflorescence were further manipulated by either decreasing or increasing the grain coverage. Two specific hypotheses were statistically tested for aflatoxin accumulation in grain from inoculated inflorescences: aflatoxin accumulation changes in maize and sorghum inflorescences when they are modified from their natural state, and aflatoxin accumulation varies between natural and artificial covering of inflorescences. Aflatoxin data collected from 2 yr of inoculating Aspergillus flavus into maize ears and sorghum panicles indicated that modifying the inflorescences of both species had the largest effects in increasing aflatoxin amounts. Substituting natural coverage of maize and bagging sorghum panicles increased aflatoxin accumulation significantly. This study demonstrated that sorghum may accumulate substantial aflatoxins when it is inoculated and the inflorescence is modified by covering with a paper pollinating bag. Substituting maize husks with paper pollinating bags also substantially increased aflatoxin accumulation in maize.