This study evaluates the influence of crop seasons, cultivation regions, and traditional agricultural practices on the occurrence of F. proliferatum and A. flavus in the rice chain in the Mekong Delta, Vietnam. A survey on pre- and post-harvest practices was performed from 2017 to 2019 in parallel with sampling. Results showed that F. proliferatum (36.3%) and A. flavus (10%) were predominantly present throughout the rice chain. These fungi frequently occurred in winter-spring and autumn-winter crops in Can Tho paddy. Especially, F. proliferatum appeared both on the field and during transportation (50-100%), while A. flavus presented at all stages (10-33%). The occurrence of F. proliferatum reduced 70-27% after drying, depended on the seasons, compared to field and transportation stages and could not be detected anymore at further stages. Applying poor pre-harvest agricultural practices such as the use of certain varieties (Jasmine, DT8 varieties), combination of fertilizers (organic-inorganic), fields with crop debris, unhygienic boats, and delayed drying time of 8-12 h or 12-28 h resulted in an increase in fungal contamination on paddy. This study provides a detailed description of fungi contamination in crop seasons, cultivation regions, and agricultural practices, which may help in understanding the fungal dynamic and allow identification of good agricultural practices to mitigate the fungal contamination and potential mycotoxin production.
Keywords: Aspergillus flavus; Fusarium proliferatum; Mekong Delta; post-harvest; pre-harvest; rice chain; seasons.