Intoxication of Mesotrione in Corn Inoculated with Azospirillum brasilense and with Application of Plant Growth Regulators

Abstract

ABSTRACT: The objective of this study was to evaluate the effect of intoxication by mesotrione herbicide on the initial development and yield of maize after seed inoculation or foliar spray application with Azospirillum brasilense and application of plant regulators. Therefore, three experiments were performed: one under greenhouse conditions and two under field conditions, in different locations. In all experiments, a randomized block design was used with a 2 x 4 factorial arrangement, representing presence (192 g ha-1) or absence of mesotrione and four treatments corresponding to the control; seed inoculation with A. brasilense; foliar spray application of A. brasilense; foliar spay application of auxin + gibberellin + cytokine (AX + GA + CK), and foliar spay applications with mesotrione were carried out at the V3 stage of the crop. The results from the greenhouse experiment, with mesotrione application, were intoxication of 7.12%, which reduced total chlorophyll content by 10.15% and carotenoid content by 75.86%, leading to reductions in gas exchange and chlorophyll a fluorescence, and increased activity of antioxidative enzymes. Under field conditions, the treatments did not reduce the effects of intoxication during the initial development of maize crop and did not increase crop yield. It was concluded that the use of A. brasilense and plant regulators did not protect maize against mesotrione intoxication in the initial development, nor did it increase yield.