Among the technologies for remediation of contaminated soils, the phytoremediation is a feasible approach. The first step towards to the implementation of this strategy is the selection of plants with potential to be used in areas that need remediation. The aim of this study was to evaluate the potential for phytoextraction of copper (Cu) by sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), crotalaria (Crotalaria juncea) and jack beans (Canavalia ensiformis). The experimental design was in randomized blocks, and treatments consisted of 0.8, 3.9, 19.7 and 98.4 µmol L-1 of Cu in the nutrient solution. Thirty days after the beginning of the treatments, the leaf gas exchange was measured in mature leaves. Then, the plants were harvested, separated into shoot and root system for determining dry matter and Cu accumulation. The treatment with 98.4 µmol L-1 of Cu markedly impaired shoot and root growth. Stomatal conductance, leaf transpiration rate and net CO2 assimilation were not affected until the treatment with 19.7 µmol L-1 of Cu in the nutrient solution. Cu content and accumulation in plant tissues were well related to the metal concentration in the nutrient solution, with higher values in the roots than shoots. Although the preferential accumulation of Cu in the roots and reduced transport to the shoot contribute to enhance plant tolerance to this metal, it limits the use for Cu phytoextraction. Jack bean had the greatest Cu concentration, accumulation and transport of Cu to the shoot. Thus, this plant species has potential to be employed in programs of Cu phytoremediation.
soil descontamination; Canavalia ensiformis; Pennisetum glaucum; Sorghum bicolor; Crotalaria juncea
