Uso de leguminosas na fitorremediação de solo contaminado com sulfentrazone

Abstract

Resíduos de sulfentrazone podem permanecer no solo por cerca de dois anos, oferecendo risco de contaminação a lençóis freáticos e impossibilitando o cultivo de espécies susceptíveis. Diante disto, a fitorremediação pode representar uma opção para a descontaminação de áreas que sofreram com intensas aplicações deste herbicida. O presente trabalho avaliou o potencial remediador das espécies Crotalaria juncea, Canavalia ensiformis, Cajanus cajan e Cajanus cajan (anão), com relação ao herbicida sulfentrazone, utilizando-se o milheto (Pennisetum glaucum) como planta bioindicadora. O experimento foi instalado em casa-de-vegetação e os tratamentos compostos pela combinação entre as quatro espécies citadas, além da testemunha, e quatro doses de sulfentrazone (0 g i.a. ha-1, 200 g i.a. ha-1, 400 g i.a. ha-1 e 800 g i.a. ha-1). Foram avaliadas a altura de plantas, fitotoxicidade ao sulfentrazone e biomassa fresca e seca da parte aérea. Quando P. glaucum foi cultivado após C. juncea, apresentou maior ganho em biomassa e maior altura, e os sintomas de fitotoxicidade foram menos acentuados. C. juncea apresentou a maior capacidade de fitorremediar solos contaminados com sulfentrazone.

Sulfentrazone Phytoremediation Under Field Conditions

“…The constant supply of organic material through the use of green manure ensures the maintenance of organic matter quality and hence, soil carbon and nitrogen stocks (RIBEIRO et al, 2011;WIESMEIER et al, 2015). Madalão et al (2012) observed an increase in biomass production when C. juncea had been cultivated prior to P. glaucum, allowing P. glaucum to develop in a previously sulfentrazonecontaminated soil. Smaller reductions in fresh and dry mass were achieved in soil dosed with sulfentrazone up to a 400 g ha -1 a.i., 200 g ha -1 a.i., respectively, compared with non-remediated soil.…”

“…glaucum plants displayed larger stem diameters when cultivated in soil that had been previously cultivated with C. ensiformis in comparison with weeding alone, regardless of the sulfentrazone dose assessed (Table 3). In a study conducted in a greenhouse, Madalão et al (2012) selected C. juncea as the species that led to the best development of P. glaucum cultivated after phytoremediation, compared with the control without phytoremediation.…”

“…In recent years, especially in Brazil, studies involving phytoremediation, in addition to its environmental relevance (MADALÃO et al, 2012;SANTOS et al, 2013b), have received great stimulus for use in agricultural areas.…”

“…Some studies have shown that it is possible to use plants to reduce the phytotoxicity of herbicides (the carryover effect) to susceptible crops grown in areas that have received such compounds (SANTOS et al, 2007;ASSIS et al, 2010;BELO et al, 2011;MADALÃO et al, 2012;MONQUERO et al, 2013). This reduction indicates that phytoremediation may shorten the time required before an area becomes available for the cultivation of said species (NASCIMENTO et al, 2015), which can lead to greater optimization of land use, with greater economic returns for agricultural activity.…”

Alternatives for remediation and decontamination of soils from Brazil

“…Working with leguminous crops in soils contaminated with herbicides, revealed that Crotalaria juncea showed high phytoremediation capacity of the contaminated soils at levels up to 400 g ha -1 of active ingredient (Madalão et al, 2012), in a general aspect related to the removal of heavy metals, some plant species have high efficiency, as mustard (Brassica hirta), peanuts (Arachis hypogaea), broccoli (Brassica oleracea), buckwheat (Fagopyrum esculentum Moench), vetiver grass or smell (Chrysopogon zizanioides L.), among others (Accioly and Siqueira, 2000). These data are presented in Table 2.…”