Crop Sequence Effects on Native Populations of Trichoderma spp. in No-till Agriculture

Agriculture has experienced a strong process of changes that have led to an increase in crop diseases caused by necrotrophic pathogens. Several studies demonstrated that by managing beneficial microorganisms, it is possible to reduce the impact of plant diseases. Based on this, the objective of this study was to determine the effect of field crops on the population of Trichoderma spp. in soil and straw in a no-till cropping system. The population of Trichoderma spp. was monitored in an experiment with four different crop sequences. Samples of soil and crop debris were collected in spring and fall, over three consecutive years. The population density of Trichoderma spp. was determined by dilutions with plate counts method. In addition, soil chemical properties were determined for each treatment. Barley debris showed the highest population density of Trichoderma spp. in relation to other crop debris. Different cropping sequences significantly affected the population density of this fungus in the soil. However, they had no effect on the soil chemical properties, and no association was found between these variables and the population of Trichoderma spp. These results confirm the possibility to handle the native population of Trichoderma spp. through the components of the crop sequences and indicate that conducive environment may support higher populations of Trichoderma. The identification of those environments enhancing Trichoderma could indicate better conditions where inoculations of this antagonist might have higher chances of success.