Mycotoxigenic fungal growth within stored maize (Zea mays L.) at different storage altitudes and durations

Abstract

In this study, the interactive effect of maize (Zea mays L.) storage altitude, storage duration, and initial moisture content on the invasion of mycotoxigenic fungi on maize stored within woven polypropylene bags was evaluated. The direct plating method on potato dextrose agar media was used for the isolation of maize kernel fungi, and the identification was done morphologically. The study result revealed that Aspergillus spp., Fusarium spp., and Aspergillus flavus were identified at all storage altitudes (1500, 1800, and 2200 meters above sea level (m.a.s.l.)), and the level of fungal growth was affected by storage duration and initial moisture content. There was a relatively higher density of Aspergillus flavus at lower altitudes. Aspergillus flavus growth was significantly increased by prolonging maize storage duration at 1500 m.a.s.l. altitude; kernel infection increased from 33% to 47% between the 4th and 8th months of storage. Similarly, there was a higher incidence of Aspergillus spp. at the lower altitude; after 8 months of storage, the relative density of Aspergillus spp. was 69% at 1500 m.a.s.l. altitude. After 8 months of storage, the highest kernel infection with Fusarium spp. (53%) was observed at 2200 m.a.s.l. (the highest altitude). There was a decrease in Fusarium spp. kernel infection from the 4th month (27%) to the 8th month (7%) at 1500 m.a.s.l. altitude. The relative density of the fungi increased with an increment in the initial storage moisture content of maize. Hence, the existence of Aspergillus spp., Aspergillus flavus, and Fusarium spp. in maize stored with different initial moisture contents (12% to 15%), various sites of an agro-ecological zone, and storage durations emphasizes the need to utilize climate-smart post-harvest technologies for storing maize for more than 4 months in woven polypropylene bags, particularly at lower altitudes (1500 m.a.s.l.) to minimize aflatoxin contamination.