Prospecção de Trichoderma spp. com potencial de biocontrole de fitopatógenos e solubilização de fósforo e potássio

Abstract

Root diseases caused by phytopathogenic fungi represent one of the major phytosanitary problems in soybean (Glycine max L.) cultivation, leading to reduced plant development and yield losses. In this context, the use of biological agents has emerged as a sustainable alternative for managing these diseases. This study aimed to screen Trichoderma spp. isolates for their potential to biocontrol phytopathogenic fungi associated with soybean crops, as well as to evaluate their phosphorus and potassium solubilization capabilities. To isolate the biological agents, baits consisting of rice colonized by Fusarium tucumaniae were deployed in vegetated areas in the municipalities of São João and Nova Prata do Iguaçu, Paraná. After the baits remained in the field for 20 days, the material was collected and sent to the laboratory for microorganism isolation using Potato Dextrose Agar (PDA) médium. Subsequently, the isolates were molecularly identified as Trichoderma scalesiae (T.s V1), Trichoderma scalesiae (T.s V4), Trichoderma breve (T.b V11), Trichoderma harzianum (T.h NP1), and Trichoderma harzianum (T.h NP2). Biocontrol potential was evaluated on PDA medium through direct confrontation assays against the phytopathogens Macrophomina phaseolina, Sclerotinia sclerotiorum, Rhizoctonia solani, and Fusarium tucumaniae. Phosphorus and potassium solubilization capacities were evaluated in vitro using NBRIP medium and modified Pikovskaya medium, respectively. The experiment followed a completely randomized design with three replicates per treatment. Data were subjected to the Shapiro-Wilk normality test and regression analysis using Rbio software. The results demonstrated that all isolates exhibited biocontrol potential, promoting reductions of up to 68% in the mycelial growth of Rhizoctonia solani, 56% for Fusarium tucumaniae, 46% for Sclerotinia sclerotiorum, and 41% for Macrophomina phaseolina. During the interaction assays, mechanisms involving competition for space and nutrients, as well as mycoparasitism, were observed. Furthermore, the isolates formed solubilization halos and altered the color of the culture media, indicating potential for phosphorus and potassium solubilization. It is concluded that the prospected Trichoderma spp. isolates show potential for the biocontrol of phytopathogenic fungi and for nutrient availability, demonstrating their relevance as a sustainable alternative for agricultural management.