Bioassay for Determining Persistence of the Herbicide Saflufenacil in an Oxisol

Abstract

Persistence of an herbicide is defined as the ability to maintain the integrity of its molecule and chemical, physical, and phytotoxic properties in the environment where it was applied. Knowledge of persistence has implications both for the toxicity generated on species grown in succession and for the period in which the herbicide controls weeds. This study aimed to assess the persistence of the herbicide saflufenacil in an Oxisol by means of bioassays. Two experiments with the application of 29.4 g ha-1 of saflufenacil were carried out under field conditions: the first in the 2011/2012 season and the second in the 2012/2013 season. Soil samples were collected at depths of up to 10 cm at different times after application. Subsequently, two bioassays were carried out in a greenhouse by using beet (Beta vulgaris L.) and cucumber (Cucumis sativus L.) as bioindicators. The studies were carried out in a completely randomized design with four replications. Treatments consisted of periods after saflufenacil application (0, 5, 10, 15, 25, 35, 50, and 100 days). The crop was also considered as a factor. Stand, height, and phytotoxicity of plants were assessed in both agricultural seasons at 14, 21, and 28 days after sowing (DAS), as well as shoot fresh (SFM) and dry matter (SDM) at 28 DAS. In general, saflufenacil persistence was between 25 and 35 days. Beet was more sensitive to the presence of saflufenacil in the soil when compared to cucumber. Herbicide effects were higher in the 2012/2013 season when compared to the 2011/2012 season.

Uso de bioindicadoras vegetais para identificação de resíduos de herbicidas no solo

“…O bioensaio é utilizado para identificação de efeitos alelopáticos entre espécies vegetais, mas as principais aplicações são voltadas para o reconhecimento de resíduos de herbicidas no solo (Cândido et al, 2010;Nunes & Vidal, 2009;Ribeiro et al, 2019). Essa técnica tem sido estudada em avaliações de persistência, lixiviação, identificação de espécies Research, Society and Development, v. 9, n. 9, e999998123, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i9.8123 fitorremediadoras e potencial ocorrência de carryover (Dan et al, 2010;Diesel et al, 2019;Vasconcelos, 2017;Savaris et al, 2019;Souza et al, 2000). A realização do bioensaio apenas é possível com a utilização de uma espécie bioindicadora (Santos et al, 2013).…”

Seleção de espécies bioindicadoras de resíduos de flumioxazina e saflufenacil no solo

“…O flumioxazina é um produto não-iônico, possui solubilidade em água de 1,79 mg L -1 a 25°C e pressão de vapor de 2,41 x 10 -6 mmHg a 22°C, sua meia vida no solo é de aproximadamente 22 dias (Carbonari et al, 2010). O saflufenacil é um ácido moderado com pKa de 4,3, solubilidade em água em pH 5 e 7 de 30 mg L -1 e 2100 mg L -1 respectivamente, e meia vida no solo entre 7 a 35 dias (Diesel et al, 2019). Em plantas pulverizadas com flumioxazina e saflufenacil, a protoporfirina IX é acumulada fora dos plastídios, interagindo com o oxigênio e a luz, formando oxigênio singleto, danificando o tecido foliar pela peroxidação lipídica.…”