Manejo do paraquat na pré-colheita de sementes de soja: produtividade e qualidade física

Abstract

The study aimed to evaluate the physical quality and soybean productivity produced under the influence of paraquat herbicide applied pre-harvest at different growth stages of the plants. The experimental design was randomized blocks with five treatments and five replications. The treatments were five times pre-harvest desiccation, which corresponded to five dfferent growing stages: being R5.5 (most pods between 75% and 100% filling - 93 days after sowing - DAS), R6 (pods with full filling 100% and green leaves - 100 DAS), R7.1 (start 50% yellowing of leaves - 104 DAS), R7.3 (more than 75% of yellow leaves - 109 DAS), R8. 2 (more than 50% defoliation preharvest - 112 DAS). They evaluated the retention of seeds on sieves, weight of a thousand seeds and the yield of seeds. The size of the seeds was affected by the application of Paraquat in plants in R5.5 stages, R6.0 and R7.1 occurring higher percentage of retention on screens 5.0mm and 5.5mm. The mass of a thousand seeds and productivity were reduced by application of the product in R5.5 and R6.0 stages compared to other treatments. The application of paraquat in soybean plants in stages R5.5, R6.0 and R7.1 reduces the size, weight and seed yield compared to application in R7.3 and R8.2 stages. The physical quality of seeds and plant productivity is negatively impacted, as the time of application of the product.