Potencial de espécies vegetais na remediação de solo contaminado com sulfentrazone

Abstract

-The aim of this work was to evaluate the efficiency of plant species in the remediation of a red-yellow Hapludalf contaminated with sulfentrazone. The work was conducted at two stages. At the first, the growth of Helianthus annus, Canavalia ensiformis, Dolichos lab lab and Arachis hypogaea was evaluated in soil contaminated with sulfentrazone. At the second stage, a species (sorghum) indicator of residues of this herbicide was sown in the same soil. At the first stage, pots containing 6.0 kg of substrate were used. After the pots were irrigated, the herbicide was applied on the soil surface. One day after the application, the vegetal species were sown. These species were collected 100 days later and stove-dried for determination of shoot dry matter accumulation. At the second stage, soil samples of 3.0 kg were collected from each pot where the species indicator of sulfentrazone residues was cultivated. At 20 and 50 days after emergence, the intoxication of the sorghum plants was visually determined and the shoot dry matter of these plants was determined 50 days after emergence and 50 days after the first cut. The production of shoot dry matter of H. annus, C. ensiformis, D. lab lab and A. hypogaea was not affected, indicating that all species were tolerant to sulfentrazone. However, H. annus showed greater capacity for remediation of soil contaminated with this herbicide.

Susceptibilidade de espécies de plantas com potencial de fitorremediação do herbicida sulfentrazone

“…No entanto, nas doses seguintes (400 g ha -1 , 800 g ha -1 e 1.600 g ha -1 ), nenhuma planta dessa espécie sobreviveu à atividade do herbicida no solo. Outra espécie que também se recuperou consideravelmente, mas apenas na dose de 200 g ha -1 , foi C. breviflora, passando de aproximadamente 65% de fitotoxicidade, na pri- Belo et al (2011) Figura 1. Sintomas de fitotoxicidade das plantas (%), aos 30 dias após a semeadura, em função da dose do herbicida sulfentrazone.…”

“…Para estudos de fitorremediação com o herbicida picloram, Panicum maximum cv Tanzânia e Eleusine coracana foram selecionados por Carmo et al, (2008). Já Belo et al (2011), em trabalho preliminar, um dos raros na literatura referenciando o sulfentrazone, descrevem as espécies Helianthus annus e D. lablab como potencialmente fitorremediadoras de solos contaminados com esse herbicida. Todos esses trabalhos evidenciaram que as espécies que toleraram os herbicidas no solo, também tiveram, posteriormente, desempenho satisfatório como fitorremediadoras.…”

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.…”