Phytoremediation of cadmium contaminated soils using sunflower (Helianthus annuus L. var. Sunbright)

Abstract

The aim of the present research was to determine the accumulation, distribution and tolerance of sunflower plants to cadmium (Cd) contaminated soils. The research consisted of two pot experiments under greenhouse conditions. In Experiment 1, concentrations of 0, 10, 15, 20, and 25 mg Cd kg-1 soil were tested and the height, dry matter production and Cd concentration in root, stem, leaf, and inflorescence were evaluated at 84 DAS (day after sowing). In Experiment 2, the concentration was 20 mg Cd kg-1 soil and the concentration of Cd in the same organs was evaluated at 35, 49, 63, 75, and 84 DAS. Cadmium doses had no effect on plant height or dry matter production, the tolerance index (TI) being equivalent to 1, which demonstrated its high tolerance for this metal. In general, it was found that increasing doses of Cd in the soil increased Cd concentration in the plant. Independent of the time of evaluation, the root concentrated more Cd due to a low translocation towards the aerial zone. The bioconcentration factor (BCF) was greater than 1 under the different doses of Cd. As for the translocation factor (TF), it was less than 1 in both experiments. According to the TF and BCF values found, sunflower would behave as a phytostabilizer below 25 mg Cd kg-1 soil.