Effects of drying and storage conditions on the seed fungal flora in peanut production and biological control of aflatoxin production by Aspergillus flavus

This research aimed to evaluate the impact of post-harvest drying and storage conditions on seed moisture content, fungal community structure, and aflatoxin contamination in peanut production, as well as to assess the efficacy of selected antagonist fungi and commercial biological agents in suppressing Aspergillus flavus–induced aflatoxin biosynthesis under field conditions. Mean moisture contents were determined as 15.96% at harvest, 13.85% during sun-drying (sergen), and 5.87% during storage. Detailed mycological analyses revealed that the predominant fungal genera were Aspergillus spp. (44.5%) and Fusarium spp. (30.1%) during harvest; Aspergillus spp. (47.3%) and Fusarium spp. (10.4%) during drying; and Rhizoctonia spp. (32.4%) and Penicillium spp. (29.6%) during storage. Based on HPLC analysis, total aflatoxin levels ranged between 0.039–2.209 µg/kg in drying-stage samples and 0.015–14.456 µg/kg in storage samples. In vitro dual culture assays demonstrated that Trichoderma gamsii and T. afroharzianum isolates exhibited the highest antagonistic activity against toxigenic A. flavus and A. parasiticus, achieving inhibition rates of up to 90%. Analysis of variance indicated highly significant differences among treatments in both field locations (p < 0.001). At the Kesik site, Talaromyces verruculosus yielded the highest mean productivity (506.25 kg/da), while in Camuzcu, T. gamsii, Bacillus subtilis (Serenade®), and the atoxigenic A. flavus strain AFX1 (sorghum) were statistically grouped as the top-yielding treatments. Across both sites, AFX1 (sorghum and wheat-based) resulted in the lowest aflatoxin concentrations. While Bacillus subtilis demonstrated notable efficacy in Kesik, its performance declined under Camuzcu conditions. These findings underscore the environmental sensitivity of biocontrol agents and highlight the critical role of local adaptation in effective aflatoxin management strategies. Keywords: Peanut, aflatoxin, Aspergillus flavus, biological control, mycotoxin