Potencial fitorremediador para cromo de Handroanthus chrysotrichus (Mart. ex DC.) Mattos e Handroanthus heptaphyllus (Vell.) Mattos

Abstract

Brazil and the world have been facing serious soil contamination problems in the last decade. Among the numerous contaminants are heavy metals, which in turn may or may not be essential for human and plants development. Among the elements is chromium (Cr) which in high concentrations causes serious problems to human health. Some of the contaminated soil used in agriculture requires the knowledge of simple, efficient and cost-effective remediation technicians such as phytoremediation. In this context, the objective of the present study was to evaluate the phytoremediation potential of the Handroanthus chrysotrichus (yellow Ipe) and Handroanthus heptaphyllus (purple Ipe) species and the effect of Cr on plant physiology and biochemistry. The experiments were carried out at the greenhouse and at the Plant Physiology and Plant Nutrition Laboratory belonging to the Department of Biology of the Federal University of Santa Maria (UFSM), Santa Maria campus (RS). Part of the seeds of both species underwent germination test under the conditions of treatments of 0, 50, 100, 150 and 200 mg L-1 of Cr6+, while others were germinated and after initial growth sent to hydroponic system in greenhouse and submitted to the same treatments. After exposure to the different treatments, samples were collected and analyzed for physiological variables (fresh and dry biomass, plant height, root system biometric variables, leaf area and leaf number), biochemical (antioxidant enzymes, hydrogen peroxide content, lipid peroxidation and photosynthetic pigments) and photosynthetic variables. Toxicity symptoms were observed in the two species studied mainly at levels above 100 mg L-1. The germination of H. heptaphyllus was less affected that H. chrysotrichus, however, yellow ipe had greater tolerance to the presence of Cr in the root and leaf area, average root diameter, peroxidase enzyme activity, lipid peroxidation and presence of H2O2 in the roots, water use efficiency and internal CO2 concentration. It is possible to register that two species can be used as bioindicators of high temperature contamination Cr. However, even activating their defense motors and overcoming damage caused by damage above 100 mg L-1 has not been visualized, their use in projects of a Recovery of contaminated areas may still be suggested using previous studies of contamination of the area.