MAIZE STOVER DEGRADATION UNDER THE INFLUENCE OF HALOXYFOP-METHYL UNDERDOSES

Abstract

One of the major constraints to sustainable tillage is the rapid decomposition of the dry matter. The mechanism known to facilitate this process is the interference in the metabolic pathways of lignin polymers from spraying herbicide underdoses. This study has aimed to verify the effect of underdoses of haloxyfop-methyl in the synthesis of lignin and correlate the interference of this phenolic compound in the decomposition of maize stover. Two preliminary experiments were carried out in a greenhouse to set up the best underdoses to be applied in the yield area experiment. The treatments in the first experiment consisted of: 0; 2.5; 5 and 10 g a.i. ha(-1) of haloxyfop-methyl herbicide. And in the second experiment: 0; 0.625; 1.25 and 2.5 g a.i. ha(-1) of haloxyfop-methyl herbicide. In all treatments were added 0.5% (v:v) of the surfactant ethoxylated nonyl phenol + dodecylbenzene sulfonic acid (Aterbane). For the yield area experiment, the underdoses used were 0, 0.625, 1.25 and 2.5 g a.i. ha(-1) of haloxyfop-methyl plus 0.5% (v: v) of the surfactant Aterbane. There was an increase in lignin content in the greenhouse experiments with the underdose 0.625 g a.i. ha(-1). In this underdose, change in maize plants growth was not observed. In the field, the concentration of 0.625 g a.i. ha(-1) of haloxyfop-methyl increased in 13% the lignin content without interfering in height and biomass of the plants, contributing to delay the decomposition rate in 4% in the residual stover.