Fitorremediação de solos contaminados com clomazone por feijão-de-porco (Canavalia ensiformis (L). DC.)

Abstract

Herbicides are the most used pesticides in Brazil and some remain in the soil for longer than necessary for the crop cycle in which they were used. Clomazone is a widely used herbicide and very dangerous to the environment, it is persistent in the soil and soluble in water. Phytoremediation is a technique that aims to decontaminate soil and water through the use of plants and their associated microbiota. Several plants have been tested as remediators for soils contaminated with herbicides, including jack beans (Canavalia ensiformis). Therefore, the objective of this work was to evaluate the phytoremediation potential of jack beans in soils of different textures contaminated with clomazone. The experimental design was in completely randomized blocks, in a 4 x 5 factorial scheme, with 4 replications. The soils used were Red Yellow Argisol (PVA), Melanic Gleisol (GM), Red Yellow Latosol (LVA) and Quartzarenic Neosol (RQ). The doses used were: 0, 1, 10, 50 and 100 kg a.i. ha-1 . The following variables were evaluated: plant height, stem diameter, chlorophyll content, leaf area, root and shoot dry matter mass and visual phytotoxicity. The jack bean was cultivated for 75 days and subsequently the bioindicator plant (Cucumis sativus) was cultivated for 30 days. Jack bean plants grown in soils that received doses of 50 and 100 kg a.i. ha-1 died, regardless of the soil. An increase in damage to the vegetative parts was observed when the herbicide dose was increased. In the bioassay with cucumber, the plants had no change in chlorophyll content, regardless of the dose and soil, however, phytotoxicity was observed in the plants, with the plants grown in LVA being those that showed the highest percentage of phytotoxicity. Jack beans have potential for phytoremediation of the herbicide clomazone up to a dose of 10 kg a.i. ha-1 . Greater phytoremediation occurs in the Melanic Gleisol, followed by the Red Yellow Argisol and Quartzarenic Neosol and lower in the Red Yellow Latosol.