Inoculantes à base de Trichoderma sp.: impacto das estratégias de produção por fermentação sólida e fermentação líquida submersa no desempenho e estabilidade para o manejo de doenças da soja

Abstract

The increasing global demand for bioenergy, fibers, and food drives the search for more sustainable agricultural practices, especially in soybean cultivation, where phytopathogens like Sclerotinia sp., Colletotrichum sp., Fusarium sp., and Phomopsis sp. cause significant losses. In this context, biological control emerges as a promising alternative, with Trichoderma sp. standing out as both a biocontrol agent and a growth promoter. This study's main objective was to comparatively evaluate the production, stability, and biocontrol efficacy of Trichoderma sp. obtained by solid-state fermentation (SSF) and submerged fermentation (SmF) for soybean disease management. For this purpose, Trichoderma sp. products were produced and characterized by both methods. The viability and shelf life of crude (pure conidiospores and pure fermentation broth) and formulated (wettable powder and concentrated suspension) samples were monitored under different temperature conditions. Additionally, in vitro biocontrol efficacy was analyzed in soybean seed treatment against the aforementioned phytopathogens, comparing Trichoderma sp. products with a commercial fungicide and a negative control. The inhibitory effect of secondary metabolites (volatile, non-volatile, and thermostable) from Trichoderma sp. SmF broth on phytopathogens was also evaluated. Stability results indicated that SSF products (pure conidiospores and wettable powder formulations) showed a longer shelf life (up to 28 and 27 months, respectively, under refrigeration/freezing), while SmF fermentation broth and concentrated suspension formulations (both from SSF and SmF) demonstrated reduced viability (1 to 3 months), highlighting the superiority of solid-state fermentation for stability. In in vitro assays, SmF-obtained Trichoderma sp. excelled in controlling S. sclerotiorum (26.38% inhibition) and F. crassistiptatum (23.49% inhibition), outperforming the commercial fungicide. In contrast, SSF Trichoderma sp. was more efficient against C. truncatum (44.6% inhibition). For P. longicolla, both Trichoderma sp. treatments surpassed the commercial fungicide, which showed negative inhibition. The evaluation of secondary metabolites revealed that volatile compounds showed no significant inhibition. However, non-volatile and thermostable metabolites from SmF fermentation broth exhibited significant (46.37%) and moderate (18.53%) inhibitory effects, respectively, specifically against Phomopsis longicolla. These findings reinforce the potential of Trichoderma sp. as an effective and sustainable bio-input for soybean disease management. The choice of fermentation method should consider the target phytopathogen and storage conditions to optimize its application and field performance.