CONTROLE BIOLÓGICO DE Bipolaris oryzae EM ARROZ VERMELHO

Abstract

Rice (Oryza sativa L.) is considered one of the most important crops in the world, contributing significantly to human consumption. One of the factors that contribute to reduce the production of this crop is the occurrence of diseases, which can cause severe damages. In this context, the causal agent of the brown spot, the fungus Bipolaris oryzae, can be highlighted, which can cause losses of up to 80% in the planting areas. In view of the above, the objective was to determine the effect of Trichoderma spp. in the control of B. oryzae in red rice seeds. The isolates of Trichoderma spp. used in the experiment were obtained from isolation of seeds of cultivated plants and derived from commercial product. The inoculum was obtained from infected seeds. A direct comparison of antagonist versus pathogen was performed, including cultures matching, volatile metabolites, sporulation and myoparasitism, as well as physiological quality. According to the in vitro test, the isolates of Trichoderma spp. were used to evaluate their effectiveness in the control of brown spot in greenhouse using seed treatment methods and foliar spraying, analyzing the incidence, reduction, severity and severity index of the disease. Transmissibility test was also carried out via seed-plant. The results showed that the isolates of Trichoderma spp. were efficient in inhibiting mycelial growth of the pathogen in vitro, producing volatile metabolites and inhibiting sporulation. Microscopic observations showed evidence of mycoparasite behavior of Trichoderma spp. about B. oryzae. A high transmission rate of B. oryzae via seed-plant was observed. In greenhouse tests, the isolates of Trichoderma spp., Significantly controlled the incidence, reduction, severity and severity index of the disease. Trichoderma spp. tested on the B. oryzae biocontrol in red rice seeds were efficient and can be used to manage the disease.