Uso de trichoderma spp. como potencial biocontrolador da antracnose da soja

Soybean is one of the main crops planted in Brazil and is considered the agricultural commodity of greatest global economic importance. Among the factors that limit crop production in Brazil, fungal diseases such as anthracnose, caused by the fungus Colletotrichum truncatum, stand out. This disease can cause losses of up to 100% of production if adequate control measures are not adopted. The use of biocontrol agents for plant diseases has been developing in recent decades and is an economically viable and environmentally sustainable alternative to chemical control. Among these organisms, the genus Trichoderma spp. stands out, with many potentially antagonistic species and diverse mechanisms of action against phytopathogens. Given the above, the objective of this study was to evaluate isolates of Trichoderma spp. for in vitro control of C. truncatum. The experiments were performed using six isolates of the species T. koningiopsis, T. asperellum and T. harzianum against one isolate of C. truncatum. Antagonism was assessed by means of the culture pairing method and production of inhibitory volatile metabolites. The growth of fungal colonies was measured at 7 and 12 days after the assembly of both tests to determine the percentage of mycelial growth inhibition (PIC). In the culture pairing test, the degree of antagonism of the Trichoderma spp. isolates was also determined according to a rating scale. By evaluating the rating scale, all Trichoderma spp. isolates obtained scores greater than zero and less than or equal to three, classifying them as potential antagonists to C. truncatum, with emphasis on the TR-25 isolate (T. asperellum) which obtained a score of 1, considered to be of maximum efficiency in controlling the pathogen in vitro. Regarding the ability to inhibit mycelial growth of C. truncatum, isolates TR-96, TR-14 and TR-25 stood out for inhibiting 56.52%, 51.26% and 51.04%, respectively, by the culture pairing method. In the evaluation of inhibition by production of volatile metabolites, it was possible to observe the biocontrol exerted by the isolates of Trichoderma spp. on the pathogen, with all isolates inhibiting the growth of C. truncatum and statistically differentiating themselves from the control. The isolates TR-35 (T. koningiopsis) and TR-155 (T. harzianum) stood out, presenting percentages of inhibition of mycelial growth of the pathogen of 30,16% and 23% on the 7th day and 37,56% and 26% on the 12th day, respectively, higher than the rest of the isolates evaluated. Keywords: Biological control. Colletotrichum truncatum. culture pairing. antibiosis.