Efeito da microbiolização de sementes com diferentes níveis de vigor, na severidade de doenças e rendimento da soja

Abstract

Soybeans have a high commercial importance worldwide, and, due to the development of numerous products derived from grains, the production per crop has been presenting significant increases. Linked to this, biotic and abiotic limiters have been causing difficulties to reach the maximum productive potential, especially the diseases, which are part of the most significant group of these and are capable of causing severe damage to soybean crop major Asian rust, downy mildew and powdery mildew. To avoid the damage caused by pathogens we can use cultural, genetic, chemical and biological control, the latter deserves to be highlighted for being effective in the control of various diseases and which consists in the use of one organism to control another, and therefore its Biocontrol agents are of great importance for research. It is in this context that the objective of this work was to verify the effects of microbiolization with Bacillus isolates on soybean seeds with different vigor levels and to evaluate the interaction of these variables on the severity of Asian rust, downy mildew and powdery mildew. yield components. The experiment was conducted in a 4 x 2 factorial (vigor x microbiolization levels), with 4 replications, in a randomized block design (DBC). For the implementation of the experiment, the seeds were submitted to microbiolization using a Bacillus isolate (RD34). The seeds used were from cultivar M6410 IPRO with 4 vigor levels: 74%, 77%, 97% and 99%. Weekly evaluations were performed to quantify the severity of diseases such as Asian rust, downy mildew and powdery mildew. These data were used to calculate the area under the disease progress curve (AACPD). The defoliation index was also evaluated and the total number of vegetables per plant, the number of fertile and infertile vegetables, as well as the grain diameter (mm), yield (Kg. Ha⁻¹) and weight of one thousand grains (PMG) were counted.) (g). Microbiolization with Bacillus isolate in seeds with different vigor levels had no effect on reducing the severity of Asian rust, downy mildew and powdery mildew. Plants from seeds with lower vigor levels showed higher severity to powdery mildew compared to plants from higher vigor levels. Higher vigor provided a larger grain diameter. Microbiolization of low vigor seeds reduced defoliation of soybean plants. The highest number of vegetables per plant was observed in plants from seeds that received the microbiolization of Bacillus isolates.