Herbicide dissipation and its effects on plants in microcosms assays

MERINI, LJ; CUADRADO, V; FLOCCO, CG; GIULIETTI, AM

Pinamar - Buenos Aires

Congreso; XLI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (S.A.I.B.).; 2005

In the last decades, the high yield expected from crop cultures and the wide implementation of “no till-system” farming techniques, lead to an extensive use of agrochemicals, like herbicides. This fact makes it very important to understand the fate of the herbicides and its metabolites in the ecosystems because their accumulation can represent a serious risk for the environment and human health. To study these complex interactions, microcosms experiments were set under laboratory conditions. Agricultural soils with and without history of treatment with herbicides were used; they were amended with different concentrations of the herbicide 2,4- dichlorophenoxybutyric acid (2,4-DB). Appropriate samples were taken in order to assess the herbicide and its metabolites dissipation and the effects of those chemicals on soil microbial communities and plants. Analysis by HPLC revealed that the soils with history of herbicide use had a faster dissipation of 2,4-DB (initial amount 5 mg/Kg) and no metabolites accumulation, when compared to soils not previously exposed to herbicides. No differences in the degradation rates were found between planted and unplanted microcosms; nevertheless, chlorophyll A/B ratio and total thiols content showed changes in leaves and roots tissues respectively, when the herbicide was present