Seleção de espécies para a fitorremedição de solos com tebuthiuron

Abstract

This work aimed to select plant species for phytoremediation of soils with tebuthiuron, to evaluate the development of bioindicators after herbicide phytoremediation, in addition, quantify their soil dissipation. The treatments were composed of ten species: hamburguer seed (Mucuna aterrima); Jack bean (Canavalia ensiformes L.); Sponge gourd (Luffa aegyptiaca L.); Calopogonio (Callopogonium mucunoides L.); Pigeon pea (Cajanus cajan L.); radish (Raphanus sativus L.); rattle pods (Crotalaria spectabilis L.); Chinese senna (Senna obtusifolia L.); leadtrees (Leucaena leucocephala L.); and castor bean (Ricinus communis L.). The experiment was carried out in a greenhouse at the Campus Engineering and Agrarian Sciences (CECA-UFAL), in pots containing 3 dm3 of soil with a sandy loam texture. The experiment was carried out in a completely randomized design, in a double factorial: plant species (10) x presence of herbicide (2), with 6 replications, in the treatment with herbicide a dose of 1.0 kg was applied pre-emergence. 1 (commercial recommendation). The evaluation of the behavior of different plant species cultivated in succession to phytoremediation of soil contaminated by tebuthiuron was carried out in bioindicator plants, among which, beans (Phaseolus vulgaris L.) and cucumbers (Cucumis sativus L.) were used and indicated the presence or absence of toxic levels of the herbicide. Quantification of the herbicide in the soil was also explored, performed by high performance liquid chromatography (HPLC) and corroborated with the data obtained by the bioindicator species. The evaluations were made in four evaluation periods (15, 30, 45 and 60 days after sowing) in phytoremediation and bioindicator species through physiological and biometric variables. The physiological variables were: SPAD index, maximum quantum efficiency (Fv / Fm) and effective quantum efficiency (YIELD) of photosystem II. Biometric variables were: plant height, number of green leaves, dry matter. Only Mucuna aterrima was tolerant to tebuthiuron, showing less interference for physiological and biometric variables, and in its cultivation, an 86.5 % decrease in the concentration of the herbicide in the soil by the HPLC method was found. Regarding bioindicator species, both cucumber and beans only developed where Mucuna aterrima was cultivated, thus indicating the potential of this species for the phytoremediation of tebuthiuron in the soil.

Keywords: Decontamination, Dissipation, Herbicides.