RESUMO-Existem poucas informações quanto à fitorremediação do herbicida sulfentrazone, reforçando assim a necessidade de pesquisas que visam oferecer alternativas seguras para sua utilização em sistemas que integram a sucessão/rotação de culturas, focando a sustentabilidade da produção agrícola, sem prejuízos ao sistema produtivo e ao ambiente. Com isso, objetivou-se neste trabalho avaliar a influência da densidade populacional de Canavalia ensiformis sobre a fitorremediação de solo contaminado com o herbicida sulfentrazone. O experimento constou de um fatorial 4 x 3, no delineamento inteiramente casualizado, com quatro repetições. O primeiro fator foi constituído pela combinação de quatro densidades populacionais da espécie fitorremediadora C. ensiformis (0; 10; 20 e 40 plantas m-2) e o segundo por três doses do herbicida sulfentrazone (0; 200 e 400 g ha-1). Aos 75 dias após a emergência, as plantas foram cortadas na altura do coleto. Nesse mesmo período, efetuouse, no próprio vaso, a semeadura da espécie bioindicadora da presença do sulfentrazone, milheto (Pennisetum glaucum), na qual foram avaliadas a fitotoxicidade, a altura e a biomassa fresca e seca da parte aérea e da raiz. O cultivo prévio da espécie fitorremediadora C. ensiformis promoveu a remediação do solo contaminado com sulfentrazone. A densidade populacional mínima de C. ensiformis que possibilita o desenvolvimento do milheto é de 10 plantas m-2. Todavia, melhores resultados foram obtidos na densidade de 40 plantas m-2. Palavras-chave: Descontaminação do solo. Adubos verdes. Herbicida. Biorremediação. ABSTRACT-There is little information on the phytoremediation of the herbicide sulfentrazone. This reinforces the need for research aimed at providing safe alternatives to its use in systems that integrate crop succession or rotation, focusing on the sustainability of agricultural production, and without harming the production system or the environment. The aim of this study therefore, was to evaluate the influence of population density in Canavalia ensiformis on the phytoremediation of soil contaminated with the herbicide sulfentrazone. The experiment consisted of a 4 x 3 factorial in a completely randomised design with four replications. The first factor comprised a combination of four population densities of the species C. ensiformis, used in phytoremediation, (0, 10, 20 and 40 plants m-2), and the second of three doses of the herbicide sulfentrazone (0, 200 and 400 g ha-1). At 75 days after emergence, the plants were cut level with the collar. At the same time, pearl millet (Pennisetum glaucum), a bioindicator species for sulfentrazone, was planted in each pot, and the phytotoxicity was evaluated together with the height, and fresh and dry shoot and root biomass. Earlier cultivation of the species, C. ensiformis, helped remediation of soil contaminated with sulfentrazone. The minimum population density of C. ensiformis which allows millet to develop is 10 plants m-2 ; however, better results were obtained at a density of 40 plants m-2 .

Commonly used herbicides, such as sulfentrazone, pose the risk of soil contamination due to their persistence, bioaccumulation and toxicity. Phytoremediation by green manure species has been tested using biomarkers, but analytical data are now required to confirm the extraction of sulfentrazone from soil. Thus, the present work was carried out to analyze sulfentrazone residues in soil based on liquid chromatography with a comparison of these values to the sensitivity of the bioindicator Pennisetum glaucum. The soil samples were obtained after cultivation of Crotalaria juncea and Canavalia ensiformis at four seeding densities and with three doses of sulfentrazone. The seedlings were collected into pots, at two different depths, after 75 days of phytoremediator sowing and then were used to determine the herbicide persistence in the soil. A bioassay with P. glaucum was carried out in the same pot. High-performance liquid chromatography (HPLC), using UV-diode array detection (HPLC/UV-DAD), was used to determine the herbicide residues. The HPLC determination was optimized and validated according to the parameters of precision, accuracy, linearity, limit of detection and quantification, robustness and specificity. The bioindicator P. glaucum was more sensitive to sulfentrazone than residue determination by HPLC. Changes in sulfentrazone concentration caused by green manure phytoremediation were accurately identified by the bioindicator. However, a true correlation between the size of the species and the analyte content was not identified.

In phytoremediation programs of contaminated soil with herbicides, it is necessary to determine the appropriate density of phytoremediation species, since this practice will contribute to the efficiency of the process. The aim of this study, therefore, was to evaluate the influence of density in Crotalaria juncea on the phytoremediation of contaminated soils with the sulfentrazone herbicide. The experiment was conducted in a greenhouse using plastics pots. The treatments were the combination of density of C. juncea, (0, 60, 120 and 240 plants m-2) and doses of sulfentrazone (0, 200 and 400 g i.a. ha-1). The herbicide was applied on the pots and then the species used for phytoremediation were sown. At 75 days after emergence, the plants were cut close to the ground and discarded. Posteriorly, the bioindicator species for sulfentrazone, Pennisetum glaucum, was planted in each pot. In the absence of previous cultivation of C. juncea, the fresh mass and dry mass of shoot and root of P. glaucum were lower than those obtained with the previous cultivation. As the density of C. juncea increased, there was an increase in fresh mass and dry mass, regardless of the sulfentrazone dose applied to the soil. The earlier cultivation of C. juncea led to the remediation of the soil contaminated with sulfentrazone. The minimum density of C. juncea which allows P. glaucum to develop is 120 plants m-2.

Phytoremediation is an alternative for the decontamination of areas that have received intense applications of herbicides. This study aimed to verify the reuse possibility of Canavalia ensiformis and Crotalaria juncea as green manure and the influence of the vegetation cover after phytoremediation of soil contaminated with sulfentrazone on the growth and development of Pennisetum glaucum. Two experiments were carried out in a greenhouse. One of the experiments was conducted with C. juncea and the other with C. ensiformis, two phytoremediation species of the sulfentrazone herbicide. The experiments were set up in 4 x 3 factorial, with the first factor being four population densities of the phytoremediate species (C. juncea -0, 60, 120 and 240 plants m -2 ; C. ensiformis -0, 10, 20 and 40 plants m -2 ), and the second composed by three sulfentrazone doses (0, 200 and 400 g ha -1 ). Seventy-five days after emergence (DAE), the plants were collected by separating the aerial parts and roots to determine the sulfentrazone accumulation in the plants by using high performance liquid chromatography. Plant extract was prepared from the vegetable material and applied in pots containing washed sand, followed by the sowing of the indicative plant (Pennisetum glaucum). It was evaluated as to its phytotoxicity plant height, aerial part and roots dry matter. P. glaucum cultivated in the substrate that received leaf extract from C. ensiformis and C. juncea cultivated in soils with presence of sulfentrazone did not display any intoxication symptom to this herbicide. The extracts from Canavalia ensiformis and Crotalaria juncea were not phytotoxic to the millet, indicating that these species can be used as green fertilization after phytoremediation of the sulfentrazone in the soil.A permanência de resíduos de Canavalia ensiformis e Crotalaria juncea após fitorremediação em solo contaminado com sulfentrazone não resulta em recontaminação do solo RESUMO: A fitorremediação é uma alternativa para a descontaminação de áreas que receberam intensas aplicações de herbicidas. Objetivou-se com esse estudo verificar a possibilidade de reutilização de Canavalia ensiformis e Crotalaria juncea como adubo verde e a influência da cobertura vegetal após fitorremediação de solo contaminado com sulfentrazone sobre o crescimento e desenvolvimento de Pennisetum glaucum. Foram realizados dois experimentos em casa-de-vegetação. Um dos experimentos foi conduzido com C. juncea e outro com C. ensiformis, duas espécies fitorremediadoras do herbicida sulfentrazone. Os experimentos foram montados em fatorial 4 x 3, sendo o primeiro fator quatro densidades populacionais das espécies fitorremediadoras (C. juncea -0, 60, 120 e 240 plantas m -2 ; C. ensiformis -0, 10, 20 e 40 plantas m -2 ) e o segundo três doses de sulfentrazone (0, 200 e 400 g ha -1 ). Setenta e cinco dias após a emergência (DAE) as plantas foram coletadas separando-se a parte aérea e a raiz para determinação da acumulação de sulfentrazone nas plantas por cromatografia líquida de alta eficiência....