SENSITIVITIES OF Urochloa decumbens PLANTS TO GLUFOSINATE

Abstract

This study aimed to assess the response of Urochloa decumbens plants to different doses of glufosinate ammonium, and the sensitivity of plant population to the herbicide. Two studies were conducted, both in greenhouse and repeated at different times. In the dose-response analysis, two experiments were conducted using seven doses of the glufosinate ammonium (0, 50, 100, 200, 400, 800, and 1,600 g a.i. ha(-1)) with four replications each. In the analysis of sensitivity levels of U. decumbens to herbicide, 44 plants were sprayed with a dose of 200 g a.i. ha(-1) of the herbicide. Tissue ammonium content was determined, and injury percentage was visually assessed. Experiment data were converted to mg of ammonium per kg(-1) of fresh mass and submitted to analysis of variance, and treatment means were compared by t test (p <= 0.10). Control of Urochloa decumbens plants by glufosinate might be associated with plant tissue ammonia content, which increased as a function of herbicide application, but not linearly as a function of dose rate. Variability existed in the ammonium content among the individuals of the population of U. decumbens.