Pyroxsulam em mistura com inseticidas piretróides na cultura do trigo: efeito enzimático

Abstract

It is very common to use mixtures of different pesticides in agriculture, and the result of an association between them can be antagonism (less effect of the mixture when compared to the products applied separately), synergism (enhanced effect of the mixture) or additive (equal effects of the mixture compared to the products applied alone). The aim of this work was to verify the effect of mixtures of herbicides and insecticides on wheat development and on the catalytic activity of the antioxidant enzyme Glutathione S-Transferase (GST) in wheat plants. Two experiments were carried out involving two insecticides from the pyrethroid group: deltamethrin (5 g a.i. ha-1) and acetamiprid + fenpropathrin (30 g a.i. ha-1 + 45 g a.i. ha-1). These insecticides were applied together or in combination with the herbicide pyroxsulam (18 g i.a ha-1), simulating a tank mix and different intervals between the application of the insecticide and herbicide (3 and 7 days). For each experiment, the experimental design was completely randomized with 7 treatments and 4 replications. The results were observed using two assessment methods, one according to visual symptoms of phytotoxicity in the crop assessed at 7, 14, 21 and 28 days after application (DAA) and the other by taking samples of the leaves and roots of the wheat plants 24, 48 and 72 hours after application to assess the effects of the mixtures on the action of the GST enzyme. It can be seen in both experiments that the treatment where the insecticide was applied 7 days before the application of the herbicide showed greater phytotoxicity than the others, as well as a delay in the wheat plants' panicle emission, showing that the selectivity of the herbicide in relation to the wheat crop was affected by the insecticides.