Trichoderma spp. na qualidade do solo, supressão de doenças e nutrição de plantas

Abstract

The sustainability of agricultural systems depends on maintaining soil quality. The intensive use of soil and inputs may be leading to a process of soil degradation. Trichoderma spp., fungi widely studied for the control of plant diseases, has the potential to be used to improve the chemical, physical and biological quality of the soil and in plant nutrition. However, the promising results obtained under controlled conditions are not always obtained under field conditions. Thus, the aim of the present study was to evaluate the action of Trichoderma spp. on soil quality, disease suppression and plant nutrition, in different soils, application forms and cropping systems. For this, experiments were conducted in the field, laboratory and greenhouse and the results of the study were organized into four chapters. The results obtained in the first chapter demonstrated that the application of Trichoderma spp. by surface spraying in Ferralsols results in soil acidification, increased potassium (K) and manganese (Mn) uptake by the soybean crop, decreased white mold incidence and reduced the production of plants with symptoms Fusarium sp. + Macrophomina sp. However, it did not significantly influence the physical properties of the soil and the development and total productivity of the soybean crop. In the second chapter the application of Trichoderma spp. in the sowing furrow increased boron (B) absorption and reduced the severity of Macrophomina sp., observed by the increase in the production of plants with symptoms, resulting in a increase in crop productivity in the first year of evaluation. In the second year of evaluation, this effect was observed in plants with symptoms of Macrophomina sp. + Phomopsis sp. but did not result in differences in crop productivity. The addition of organic acids in the sowing furrow does not interfere with the action of the different Trichoderma-based products. The results obtained in the third chapter demonstrated that the application of Trichoderma spp. increased the uptake of nitrogen (N), phosphor (P), copper (Cu) and Mn in the tomato crop in Cambisol, but did not affect the development and yield components of the crop in the three tested soils: Ferralsols, Acrisol and Cambisol. The results of chapter four, in the in vitro experiment, demonstrated that the herbicide metsulfuron-methyl increased the development of the Trichoderma harzianum. T1A and the herbicides indaziflam and atrazine reduced the development of all strains of Trichoderma spp. tested: T1A, T3, T17 and T19. In the ecotoxicological test, it was observed that Trichoderma harzianum T1A contributes to the biostimulation of cucumber plants in metsulfuron-methyl contaminated soil and may contribute to bioremediation, requiring further confirmatory experiments. Thus, under the conditions in which this work was conducted, Trichoderma spp. in addition to its positive effects on the disease suppression, it affects soil quality and increases nutrient uptake; however, under field conditions, the effects of its benefits on crop productivity are not always observed, as a result of its complex interactions in the soil and plant and the edaphoclimatic conditions to which they are subjected. [resumo fornecido pelo autor]