Efeitos da deriva de agrotóxicos oriunda de atividade agrícola no município de Rio Sono (TO) e avaliação da legislação quanto a deriva dessas substâncias para a flora de áreas protegidas de imóveis rurais

Abstract

When sprayed, part of the pesticide can be lost to the environment, mainly by drift. Thus, substances such as glyphosate can reach non-target areas, such as the flora of protected areas that make up the agricultural mosaic. Since the plants are considered bioindicators, this chapter aimed to evaluate the morphoanatomic responses of Bowdichia virgilioides KUNTH. (Fabaceae) derived from glyphosate, in protected areas of rural properties in Rio Sono - TO. Two collections of plant material (leaves) were carried out in two farms, for ten individuals in the Reserve Area (AR) and ten in the Adjacent Range to Farming (FAL). The collected leaves were reserved for the accomplishment of the visual, anatomical and micromorphometric analyzes, being chosen randomly. The visual analysis was performed with the classification of five leaves, from each individual, into five classes, ranging from 0 to 100% of lesion. Subsequently, the foliar injury index (IIF) and the severity index (IS) were performed for both areas, in each collection. In the anatomical analysis five cuts were made, in the median region of five leaflets, of different leaves. After that, we performed usual anatomy techniques and used a photomicroscope to obtain images. For the micromorphometric analysis, a cut was chosen, for each of the five slides of each individual, of both areas in each collection. Subsequently, the Anati Quanti software was used to measure the thickness of each leaf tissue, such data being expressed as averages. With statistical software R, we verified the similarities of each tissue between RA and FAL, as well as between collections performed in the same area. In the visual evaluation, symptoms of chlorosis and necrosis were observed. The FAL plants, mainly in the second collection, had the highest IIFs, as well as the highest ISs. Possibly, these indices were influenced by the fact that these plants are on the edge of the area of agricultural management; and the second collection was exposed to the drift effect for a longer period, also subject to the occurrence of other drifts of more spraying in the crop. Symptoms such as cellular plasmolysis, hyperplasia, proliferation (healing tissue) and cell collapse were found. The herbicide probably provoked such symptoms, since other authors, in studies with simulation of glyphosate drift, including B. virgilioides, have verified such symptoms. In the micromorphometry, the thickness of the palisade parenchyma (PP) showed differences in the RA and FAL plants in the second collection, and in the FAL plants, in all collections. In the second collection, the differences found in the tissues of plants from different areas may have been due to the greater exposure of the FAL individuals to the sun, thus having a greater thickness. The difference between the tissues of the plants collected between the first and second collection in the FAL probably occurred due to the expressive stretching of the PP cells in the second collection. In other studies, intermediate doses in the drift simulation demonstrated an increase in PP thickness, which probably also occurred in this work. In view of these results, it was possible to observe that the glyphosate sprayed on the crop by drift has reached the protected areas of the rural properties causing visual, anatomical and morphometric changes in the plants of B. virgilioides, native to the Cerrado.