Effect of population density of Canavalia ensiformis on the phytoremediation of soil contaminated with sulfentrazone

Abstract

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 .

The residues of Canavalia ensiformis and Crotalaria juncea after phytoremediation in soil contaminated with sulfentrazone do not result in soil recontamination

“…This fact may be due to the increase in the population density of the phytoremediate species that resulted in the greater absorption of the nutrients present in the soil, which may have returned via extract to the used substrate (washed sand), and thus favoring a greater growth of the millet. Similar results were also observed by Ferraço et al (2017) when evaluating the effect of the population density of C. ensiformis on the phytoremediation of soil contaminated with sulfentrazone.…”

“…Previous studies proved the efficiency of Canavalia ensiformis and Crotalaria juncea in remediating sulfentrazone (Madalão et al, 2012a;b;2013;Ferraço et al, 2017). In the phytoremediation of soils with this herbicide, the C. ensiformis and C. juncea species are expected to be reused in green fertilization, making possible the insertion of these two in a program of rotation or succession of crops.…”

Phytoremediation of Contaminated Soil with Sulfentrazone by Different Density of Crotalaria juncea

“…In addition, the 200 g i.a. ha -1 dose corresponds, approximately, to half the dose expected to be available at the end of the cycle of an annual crop (Ferraço et al, 2017).…”

“…In a study made by Ferraço et al (2017), the efficiency of Canavalia ensiformis to decontaminate the soil contaminated with sulfentrazone increased due to the increase in the plant density, which may be due to the greater number of roots absorbing the herbicide from the soil, as well as to the greater number of plants in association to the microbiota of the soil, degrading sulfentrazone. This herbicide shows low mobility on the soil and low adsorption (Rodrigues and Almeida, 2011), and its solubility increases as the pH increases, being found mainly in the soil solution in the non-ionized form (FMC,1995), making it easier for the plants to absorb it.…”

Toxicity of Pre-Emergent Herbicides Applied via Irrigation Water in Eucalyptus Plantation

“…The mechanism of action of the herbicides sulfentrazone and flumioxazin is based on the inhibition of protoporphyrinogen oxidase (PROTOX) and has contact action with sprayed plants. Sulfentrazone effectively controls monocotyledons and dicotyledons (FERRAÇO et al, 2017), while flumioxazin can be applied pre-and postemergence for dicotyledonous weed control (RODRIGUES; ALMEIDA, 2011).…”