Avaliação ecotoxicológica de solos no cultivo de tabaco com diferentes manejos agrícolas utilizando Daphnia magna (STRAUS, 1820).

Abstract

Tobacco (Nicotiana tabacum L., 1753) is cultivated worldwide for commercial purposes, with Brazil being one of its largest producers and exporters. Its production is concentrated in the South region, highlighting the state of Rio Grande do Sul as the largest Brazilian producer. During the cultivation phases, pesticides are used to maximize crop yields. In this sense, ecotoxicology emerges as an important monitoring tool, which can be used to assess the impacts of these contaminants on the environment. Thus, the study was divided into two research articles; the first deals with a bibliometric review whose objective was to evaluate the use of ecotoxicological tests with the species Daphnia magna as a tool for soil analysis in tobacco cultivation, aiming to identify variables that can help in future research. The second is an experimental research with ecotoxicological assays using D. magna, carried out in twelve tobacco farms, in the cities of Sinimbu and Canguçu, RS, Brazil, in three different cultivation managements: conventional cultivation, semi-organic cultivation and organic cultivation, with the objective of analyzing the toxicity of soils in tobacco plantation. The results indicated that of the 108 samples analyzed, 95 were classified as “non-toxic” and the other 13 classified as “low toxic”. In conventional cultivation, the rate of samples that present toxicity was higher in relation to the other management techniques used, as 15% of the samples from conventional management showed a "low toxic" level of toxicity. For semi-organic cultivation, 9% of the samples were classified as “low toxic” and no sample for organic cultivation showed toxicity. D. magna is a promising organism for use in soil analysis, given its high sensitivity and ease of handling, and may be a very promising field for carrying out studies with ecotoxicological bioassays. In addition, based on the bibliographic surveys carried out with the aid of the bibliometric review, it is suggested to complement the ecotoxicological tests with genotoxicity tests, as they detect alterations in the genetic material that can be repaired, and that do not affect the viability or vitality of the test organism, that is, capable of detecting alterations even before causing the mortality of the specimens under study.