Lactuca sativa L.: BIOINDICADOR VEGETAL PARA AVALIAÇÃO DE TOXICIDADE DE Zn e Cu

Abstract

There is a growing concern about the presence of trace elements because of their characteristics of accumulation, migration, and transport in the soil. Even in low concentrations, trace elements can be toxic to plants, animals, and humans. Ecotoxicological studies includes toxicity tests called bioassays. Among the bioassays, the use of plants has been increasing, as these models are considered more sensitive and relatively simple when compared to studies with animals, since plants presents desirable characteristics such as rapid growth, low cost, high sensitivity, and good correlation with animal models. Because of this, they have been widely used in studies aiming at to prospect the effects of environmental pollutants. In this study we performed root growth measurements and enzymatic analyzes (response to oxidative stress) in Lactuca sativa L. (lettuce) as a strategy for the evaluation of phytotoxicity of copper sulfate (CuSO4) and zinc sulfate (ZnSO4). Five concentrations of CuSO4, ranging from 1.0 mg/L to 15mg/L, and five concentrations of ZnSO4, ranging from 5mg/L to 25mg/L were tested. Trifuraline (0.84 ppm) was used as a positive control and distilled water as a negative control. From the growth data obtained, it was possible to demonstrate that there were phytotoxic damages both in the treatments Zn C3 (15 mg/L), Zn C4 (20mg/L), Zn C5 (25mg/L), Cu C4 (10mg/L) and Cu C5 (15mg/L). However, through the evaluation of the specific activities of the enzymes guaiacol peroxidase (GPOX) and ascorbate peroxidase (APX), it was not possible to verify if there were damages caused by the treatments used.