Can species cedrela fissilis vell. Be used in sites contaminated with toxic aluminum and cadmium metals?

Abstract

Toxic metals are among the main pollutants contributing to environmental degradation. Cadmium (Cd) and aluminum (Al) stand out among these metals as extremely toxic elements. The use of native species in reforestation programs can compensate for degradation and re-establish the ecological conditions of the affected environments. Cedrela fissilis Vell., popularly known as cedar, may be used as an alternative in phytoremediation, since it is a fast-growing native woody species widely distributed in tropical America. In this study we investigated the possibility of using C. fissilis in sites contaminated with Al and Cd by evaluating morphological, physiological, and biochemical variables of seedlings grown in hydroponic system. C. fissilis seedlings were subdivided into two experiments with a completely randomized design. The first experiment evaluated the effect of four Al concentrations, namely: 0 (complete nutrient solution without phosphorus), 25, 50 and 100 mg l-1 . The second experiment evaluated four Cd concentrations, namely: 0 (complete nutrient solution), 25, 50 and 100 μM. Each sample unit consisted in a pot with four plants. Morphological, physiological and biochemical variables of seedlings were evaluated after 15-day exposure to different treatments in the hydroponic system. Aluminum concentration of 100 mg l-1 caused oxidative stress in C. fissilis seedlings, reduced shoot and root dry weight, and increased hydrogen peroxide contents, which led to lipid peroxidation. Cadmium concentration of 100 µM also damaged C. fissilis seedlings by significantly reducing root dry weight and involving the most severe effects on photosynthetic variables. Cadmium presence in the nutrient solution negatively affected morphophysio-logical and biochemical variables of Cedrela fissilis seedlings, and it was also harmful to their growth. Based on our results, the investigated species shows a sensitive behavior upon exposure to cadmium. On the other hand, C. fissilis tolerates high Al concentrations (up to 50 mg l-1 ), which suggests a moderate tolerance to this metal.