Microbiolização de sementes de arroz para redução da transmissão de Bipolaris oryzae.

Abstract

Rice is a crop largest economic importance global. However, the occurrence of diseases such as brown spot, incited by Bipolaris oryzae is responsible for great losses in yield. This study aimed to evaluate the potential of microbiolization rice seeds with different rhizobacterias: DFs185 (Pseudomonas synxantha), DFs223 (P. fluorescens), DFs306 (unidentified), and DFs416; DFs418 (Bacillus sp.) Two combination were used: DFsC01 (185 / 416/418) and DFsC02 (306/416/418) to reduce the incidence of B. oryzae staining of not staining fungi and seeds, as well as the transmission of this pathogen from seeds to seedlings. For this, we used two cultivars, BRS Pelota, more susceptible and BRS Querência, more tolerant to brown spot. The seeds were immersed in suspension (A540 = 0.5) of these bacteria, for the control the seeds were immersed in saline solution. After stirring period of thirty minutes at a temperature of 10 º C seeds were evaluated for the incidence of different fungi by blotter method. For the transmissibility experiment, this was conducted in transparent plastic boxes. In each box was colocated 25 cups with 50 mL sterilized vermiculite. In each cup was deposited a seed remaining in moist chamber at 25 ± 2 º C. It was observed that both the BRS Querência as BRS Pelota, when measured incidence of B. oryzae and fungal staining and not staining, the best treatments were DFs185 and DFs306. In general it was observed that the largest reductions occurred in BRS Querência. For transmission of disease expressed by the index of disease DFs185, DFs306 and the combination DFsC02 were the best treatments, which also resulted in increased seedling length by DFs185 and DFs306 treatments. Although more studies are needed, this study shows you that the efficiency of rhizobacteria in isolation in reducing pathogens in seeds its use in integrated disease management is possible.