DERIVA SIMULADA DE DICAMBA E 2,4-D: EFEITOS SOBRE A PRODUTIVIDADE E QUALIDADE FISIOLÓGICA DAS SEMENTES DE SOJA RECÉM-COLHIDAS E ARMAZENADAS

Abstract

With transgenic soybeans commercialization that have genes conferring tolerance to dicamba and 2,4-D herbicides, a supplement in herbicide alternatives can be used as part of a program to manage common herbicide-resistant plants. However, with increased herbicides use, the risks associated with drift problems also increase, since both dicamba and 2,4-D have small molecules that volatilize easily and cause damage to people at very low rates. The objective of this study was to evaluate the ingestion effects of dicamba and 2,4-D herbicide on soybean crop and plants physiological quality after harvesting and the passage of six months. Two experiments, each with herbicide, dicamba or 2,4-D, were conducted in the 4x2 + 1 double factorial scheme, with four rates (0.028, 0.28, 2.8 and 28 g ae ha-1) being applied in two phenological stages (V4 and R2) plus a control treatment. Genes-like germinated sprouts in soybean plants and crop production components, in addition to the seeds physiological quality, through the germination and vigor test, as a first germination count, an electrical conductivity, emergency percentage, the index emergency speed, shortly after harvest and after the storage period. The dicamba simulated drift caused in the soybean crop, affecting the vegetative development and the productivity, while not producing inhibitions in a significant way, it was not able to produce the elements of production. As dicamba sub-dimensions of training without stage V4 caused injuries of up to 41%, while in R2 the injuries reached 70%. Plant height is reduced by 61 percentage points for dicamba sublethal rates. The sum of soybean was 29 and 76 percentage points, when the drift spread in stages V4 and R2, and in the rate of 28 g ae ha-1. At 28 g ha-1 of dicamba, applied at V4 and R2, germination of freshly harvested seeds was reduced by 15 and 42%, respectively. After storage, seed treatment with 28 g ha-1 of dicamba the fine germination was reduced by 64 percent and the electrical conductivity doubled compared to the control. For emergence rate, and to obtain the seeds after storage, there was a reduction in the interaction between the sublethal rates and the application stage, with the treatments receiving an application of 2.8 and 28 g ha -1 with lower performance. The dicamba underdoses caused injury and reduced productivity, while 2,4-D sub-doses did not cause injury and did not affect soybean productivity. The soybean seeds have their physiological quality reduced by dicamba sublethal rates. Sublethal rates of 2,4-D in V4 and in R2 does not decrease the newly harvested soybean seeds germination and stored for 6 months at 20ºC, however decreases the speed and percentage of feed after storage.