PAPEL DE UM BIOESTIMULANTE NA PROTEÇÃO CONTRA A FITOTOXIDEZ DE HERBICIDAS PRÉ - EMERGENTES NA CULTURA DA SOJA

Abstract

The objective of this work was to verify the potential deleterious effect of the herbicides sulfentrazone and diclosulan on the photosynthetic metabolism in the soybean crop, and to verify the potential of the biostimulant to mitigate such deleterious effects after the application of herbicides. The experiment was installed in a randomized block design with four replications, with the treatments arranged in a factorial arrangement (3 X 2), totaling 6 treatments, the first factor corresponding to the application of the herbicides diclosulam, (29.4 g a.i. ha-1) and sulfentrazone (640 g a.i. ha-1) in pre-emergence, plus a treatment without the use of herbicides, while the second factor was composed by the absence and presence of the biostimulant in seed treatment. The evaluations were gas exchange, chlorophyll a fluorescence, and the chlorophyll a, b and total index. Through data analysis, it was possible to verify that the treatments used did not provide significant effects for the chlorophyll index. The application of herbicides and biostimulant did not influence the quantum performance of photosystem II, nor did it reduce the number of active reaction centers and, consequently, the absorption and capture of light energy, as well as the transport of trapped electrons. However, in the absence of herbicide, plants that did not receive the biostimulant presented a lower photosynthetic rate than other plants.