PRODUCTION AND MAINTENANCE OF SORGHUM STRAW BY HORMETIC APPLICATION OF HERBICIDES

Abstract

In the no-tillage system, maintaining straw over the soil is essential, especially in regions where decomposition is rapid. The objective of the work was to evaluate the application of underdoses of herbicide Glyphosate, 2,4 D and Haloxifope-P-Ester Methyl in the production and maintenance of sorghum straw to the no-tillage system. The experiment was carried out at the Exp. Água Limpa Farm, belonging to the University of Brasília. A factorial scheme 3 (Herbicides: Glyphosate; 2,4-D Dimethylamine salt; Haloxifop-P-methyl ester) x 2 (Subdoses: 4 and 6 g ia ha-1 of Glyphosate; 0.6 and 1.2 g Haloxifop-P-methyl ia ha-1; 80 and 160 g ia 2,4-D salt Dimethylamine), with four completely randomized repetitions. The treatments included a control without application of underdoses. The minor, major and control subdoses were identified by D1, D2 and D0 respectively. The treatments were applied 35 days after sowing with tractor spray, and after 100 days, lignin content (TL), dry matter mass (MMS) and grain yield were evaluated. The D2 treatment of Glyphosate presents an MMS 5.35% higher at 190 days after sowing. The same treatment increased the TL by 3% and did not differ in the productivity of sorghum grains.