Fitorremediação de solos com resíduo do herbicida diclosulam

Abstract

Residual herbicides, in some cases, can affect subsequente crops. In these situations, The use of phytoremediation species may be an alternative in the degradation of these molecules, minimizing the carryover risks. The first step in establishing if some species can be used as a phytoremediation, is check that it has tolerance to the product, for later verify its remedial effect. Against the foregoing, The present master's thesis aimed to identify plant species capable of phytoremediation the diclosulam herbicide, elucidating the biological mechanism of phytoremediation used by plants. For this, 3 different experiments were performed. In the first experiment, conducted at the Dow Agrosciences Experiment Station, it was selected, among the species Arachis pintoi, Brachiaria brizantha, Brachiaria decumbens, Canavalia ensiformis, Cajanus cajan e Crotalaria juncea, those that shows tolerance to the diclosulam herbicide. In the second experiment, conducted in the Universidade Federal Rural do Rio de Janeiro, it was evaluated the efficiency of the previously selected plant species to remediate soil contaminated with the diclosulam herbicide, using cucumber as a bioindicator plant. In the third experiment, conducted at Centro de Energia Nuclear na Agricultura (CENA/USP), it was verified if the tolerance mechanism of the two species that presented the greatest phytoremediation potential occurs due to the phenomena of absorption and / or translocation of the herbicide by the plant. The doses of diclosulam herbicide tested in the first and second experiments were 21, 42, 63, e 84 g ha-1 + control (without presence of the herbicide); And in the third experiment, the doses that were tested was 42 g ha-1 + control (without presence of the herbicide). The species Arachis pintoi, Canavalia ensiformis, Cajanus cajan e Crotalaria juncea showed a tolerance to the diclosulam herbicide at the doses tested, and the species Canavalia ensiformis, Cajanus cajan e Crotalaria juncea were efficient in the dissipation/degradation of these molecules in the soil, it is pointed out that the last two species were those that presented the greatest remedial effect. Using the 14C radiolabeled herbicide in its moleculares structure, could be inferred through the mass balance and observation of the radioimagens of the species Crotalaria juncea e Cajanus cajan that the phytoremediative action performed by these species is, probably, through phytostimulation. In addition, there is an anatomic / metabolic barrier of diclosulam translocation in the collar of these species, which gives them tolerance to this herbicidal molecule.