Fitorremediação de solos contaminados com o herbicida sulfentrazone por espécies de adubos verdes

Abstract

RESUMO:Diante das novas tecnologias, a fitorremediação apresenta-se como opção para a descontaminação de áreas que sofreram com intensas aplicações de herbicidas. O presente trabalho teve como objetivo avaliar o potencial remediador das espécies de adubos verdes crotalária-júncea (Crotalaria juncea L.), feijão-de-porco (Canavalia ensiformis (L.) DC.), feijão-guandu (Cajanus cajan L.) e feijão-guandu-anão (Cajanus cajan (anão) L. Millsp.) ao herbicida sulfentrazone. Foi utilizada a espécie mucuna-anã (Stizolobium deeringianum Bort.) como planta bioindicadora de resíduos do herbicida no solo, a qual foi cultivada em sucessão às espécies remediadoras. O experimento foi instalado em casa de vegetação, utilizando-se vasos contendo 10 dm 3 de solo coletado na profundidade de 0-0,2 m. Os tratamentos foram compostos pela combinação entre as quatro espécies citadas, um tratamento sem cultivo (controle) e quatro doses do sulfentrazone (0, 200, 400 e 800 g ha -1 ). Foram avaliados os seguintes aspectos: a altura de plantas, a fitotoxicidade ao sulfentrazone e a biomassa seca da parte aérea. A C. juncea foi a espécie mais eficiente na descontaminação do herbicida sulfentrazone em solo até a dose de 400 g ha -1 , o que não inviabiliza a continuidade dos estudos com as espécies C. cajan, C. cajan (anão) e o C. ensiformis, que apresentaram resultados satisfatórios com a utilização da S. deeringianum como planta bioindicadora. ABSTRACT: In face of the new technologies, phytoremediation is presented as an option for the decontamination of areas that have suffered with intense herbicide applications. This study aimed to evaluate the potential of remediation to sulfentrazone by green manure species, such as sunn hemp (Crotalaria juncea), jack bean (Canavalia ensiformis), pigeon pea (Cajanus cajan) and dwarf pigeon pea (Cajanus cajan dwarf). Dwarf mucuna (Stizolobium deeringianum) was used as the bioindicator plant of soil residues, which succeeded the remedial species. The experiment was carried out in a greenhouse using pots with 10 dm 3 , collected from the depth of 0-0.2 m. The treatments were composed by the combination of four green manure species and four doses of sulfentrazone (0, 200, 400 and 800 g ha -1

Microbial activity of soil with sulfentrazone associated with phytoremediator species and inoculation with a bacterial consortium

“…Moreover, the variety of exudate compounds as well as the phenological growth stage of plants may influence their effectiveness in the bio-remediation process (Santos et al 2010). The species Helianthus annuus and Canavalia ensiformis, previously identified as sulfentrazone phytoremediators (Belo et al 2011;Madalão et al 2012), display quite different morphophysiological and growth characteristics, which may result in distinct capacities for phytostimulation, as found in this study, and, therefore, for herbicide rhizodegradation in the soil.…”

“…The environmental conditions at the time of application were T = 27 °C, RH = 72%, and wind speed of 1.9 km•h −1 . One day following herbicide application, the remedial species Canavalia ensiformis (Madalão et al 2012) and Helianthus annuus (cultivar Tera 860 HO) (Belo et al 2011) were sown. Sowing was performed at 5 cm depth using 6 seeds per pot.…”

“…Through the phytoremediation process, Helianthus annuus and Canavalia ensiformis are able to reduce toxic levels of sulfentrazone in soils (Belo et al 2011;Madalão et al 2012). Phytoremediation may occur by extraction, stabilization, volatilization, accumulation or degradation of the herbicide in a plant tissue or by stimulating associated indigenous microbiota, known as phytostimulation.…”

Pseudomonas spp. as growth promoting agents of sunflower and jack bean in soil with sulfentrazone

“…After application of the herbicide, sowing of the sulfentrazone-remediating species jack bean (Canavalia ensiformis) (Madalão et al, 2012) and sunflower (Helianthus annuus) (cultivar Tera 860 HO) (Belo et al, 2011) was performed. Sowing was carried out at 5 cm depth using 6 seeds per pot.…”

“…Canavalia ensiformis, commonly known as jack bean, a legume commonly used as a green fertilizer and with a potential to remediate different herbicides, and Helianthus annuus (sunflower), an oilseed crop grown in several regions of Brazil, were selected as sulfentrazone-remediating plants and tested for the capacity and efficiency in reducing its toxic residues in the soil, through bioassays (Belo et al, 2011;Madalão et al, 2012).…”