Agrosilvopastoral system enhances suppressiveness to soybean damping-off caused by Rhizoctonia solani and alters Fusarium and Trichoderma population density/Sistema agrosilvipastoril aumenta supressividade ao tombamento da soja causado por Rhizoctonia solani e altera a densidade de populacoes de Fusarium e Trichoderma

Integrated crop-livestock systems (ICLS) are sustainable options for agricultural diversification, but there have been few studies on the influence of ICLS on soil microorganisms. This work investigated the influence of agropastoral (AP) and agrosilvopastoral (ASP) systems, compared with a non-integrated crop (CO) on the suppression of Rhizoctonia solani and on the density of Fusarium and Trichoderma propagules. In the first assay, soil samples were inoculated with R. solani and evaluated for soybean damping-off. After this, the soil was sterilized and re-inoculated with the pathogen for a new evaluation. Finally, 10% of the soil in the pots were substituted by newly soil samples collected from the same plots in the field to evaluate de suppressiveness transference by soil samples. In the second assay, native Fusarium and Trichoderma propagules were quantified in semi-selective media. Damping-off incidence in ASP was 70% compared to AP and CO. Evaluations with sterilized and transferred soil samples attributed this suppression to biotic factors. Fusarium propagules were retrieved in the ASP soil at 70% and 60% the amounts in AP and CO soils, respectively. Trichoderma propagules were retrieved in the ASP soil at 150% compared to AP, but similar to CO. The agrosilvopastoral system in the Brazilian subtropics has the potential to reduce pathogens and enhance beneficial microorganisms in the soil. Keywords: agricultural diversification, integrated crop-livestock system, soil health. Sistemas integrados de producao agropecuaria (SIPA) sao opcoes sustentaveis para diversificacao agricola, mas existem poucos estudos sobre a influencia de SIPA nos microrganismos do solo. Este trabalho investigou a influencia de sistemas agropastoril (AP) e agrosilvipastoril (ASP), comparados com lavoura nao integrada (CO) na supressao de Rhizoctonia solani e na densidade de propagulos de Fusarium e Trichoderma. No primeiro ensaio, amostras de solo foram inoculadas com R. solani e avaliadas para tombamento da soja. Em seguida, o solo foi esterilizado e reinoculado com o patogeno para uma nova avaliacao. Finalmente, 10% do solo nos vasos foi substituido por novas amostras de solo coletadas das mesmas parcelas no campo, para avaliar a transferencia da supressividade por amostras de solo. No segundo ensaio, propagulos nativos de Fusarium e Trichoderma foram quantificados em meios semi seletivos. A incidencia de tombamento no ASP foi 70% comparada com AP e CO. Avaliacoes com solo ester