Abstract

The use of herbicides for weed desiccation is what enables the no-tillage system, which increasingly stimulates the growth of the agrochemical market, in particular the class of herbicides. This study aimed to assess 2,4-dichlorophenoxyacetic acid and Glyphosate (N-phosphonomethyl-glycine) herbicides mixture persistence in soybeans of Ultisol in the Brazilian Cerrado. The study was conducted in a greenhouse with a randomized blocks design, in a factorial 6×5, being six application times (0, 3, 5, 7, 10 and 14 days before sowing) and five herbicide doses (0, 750, 1500, 2250 and 3000 g a.e. ha-1) in four replications. Herbicides were sprayed with a manual knapsack sprayer. The residual effect was assessed through emergence speed index (ESI), plant height and dry weight of shoots (DWS) and roots (DWR). The residual effect of mixtures of herbicides 2,4-D and Glyphosate on soybean in a Brazilian Cerrado Ultisol showed greater damage to plants when applied at sowing. The doses 2250 and 3000 g a.e. ha-1 were the most severe for the development of soybean plants.

Key words: Bioindicator, Glycine max, Herbicide, Persistence.