Uso de carfentrazone e diquat na dessecação em pré-colheita da soja

Abstract

Soybean [Glycine max (L). Merril] is a legume of Asian origin of immeasurable economic and food importance throughout the world, in addition to being considered the main Brazilian agricultural commodity. One of the most important stages in the production cycle of this crop, which concerns soybean growers, is the harvest and its ideal time to occur. In order to accelerate this stage and standardize the maturation of grains, producers throughout Brazil have opted for pre-harvest desiccation of soybeans. Thus, the objective of this work was to evaluate the efficiency of carfentrazone and diquat herbicides, associated or not, as alternatives to the use of paraquat in the pre-harvest desiccation process of soybean. The trial was conducted in the municipality of Uberlândia (MG) in the 2020/21 season. The design was randomized blocks and had 12 treatments and 4 replications. The treatments were: carfentrazone alone at doses 50, 75 and 100 mL ha-1; diquat also isolated at doses 1000, 1200, 1500 and 2000 mL ha-1; and four associations between these two herbicides (50+1000, 75+1000, 50+1200, 75+1200 mL ha-1). The application of the products occurred at stage R7.2 and the variables analyzed were percentage of defoliation, pod desiccation, impurity, moisture, mass of a thousand grains and yield. With the results, it was possible to conclude that diquat provided an earlier defoliation in all treatments in which it was present, advancing it by at least 9 days when compared to other treatments. In addition, this product caused a drop in the mass of a thousand grains in the treatments in which it was present; and, with the exception of two associations (50+1000 and 75+1200 mL ha-1), it also caused a drop in productivity. At 14 DAF, all treatments containing diquat, as well as carfentrazone alone at a dose of 100 mL ha-1, presented the best means for desiccation of pods. As for the impurity variable, it was not significant in the F test at a probability of 5%. There was no statistical difference between the tested treatments and the control regarding grain moisture. And, carfentrazone alone did not affect yield and provided uniformity in harvest at 14 DAF.