Uso de organominerais na severidade de mancha alvo e ferrugem asiática em soja

Abstract

Soybeans (Glycine max L. Merrill) feature prominently in Brazilian grain production, playing an important socioeconomic role in the country. However, its productivity is affected by several diseases, with target spot and Asian rust being among the main ones. The objective was to evaluate the use of organominerals on the severity of diseases. The experiment was conducted in the field in the municipality of Balsas (MA). Two soybean cultivars were used (BRASMAX Bônus IPRO and BRASMAX Olimpo IPRO). A randomized block design was adopted, arranged in a subdivided plot scheme, in the subplot there were three phosphate fertilizers [two of which were organominerals, and one phosphate fertilizer (simple superphosphate)]. And, in the subplot, doses of 0 (control), 50 and 100 kg of P2O5 per ha-1 containing 7 treatments. Disease severity assessments took place 7 days after the first, second and third application and 7, 14 and 21 after the fourth. At stage R6, defoliation was assessed and at the end of the cycle, harvesting was carried out to determine productivity. The variables analyzed in the soybean cultivars were not influenced by the doses of organominerals. However, the BMX Bônus cultivar, when receiving the treatment, 100 kg of P2O5 per ha-1 of ORG1 presented higher PMG values than the other treatments. Soils with high phosphorus levels, the absence of fertilization, control treatment, or the use of fertilization with organominerals, promoted higher productivity in the BMX Bônus cultivar, in which the treatment, with doses of 50 kg of P2O5 per ha-1 of ORG1, resulted in greater productivity.