Response of root and aerial biomass to phytoextraction of Cd and Pb by sunflower, castor bean, alfalfa and mustard.

Soil contamination originated from heavy metals is one of the global problems. Phytoremediation is a more advanced approach compared with physicochemical methods for their cheap and “green” characters. In this paper, sunflower (Helianthus annuus L.), mustard (Brassica juncea L.), alfalfa (Medicago sativa L.), castor bean (Ricinus communis L.) were used to test the bioaccumulation of Cd and Pb in hydroponic culture. The results showed that roots and aerials of these plants had dissimilar ability to uptake heavy metals. Moreover, the translocation of heavy metals in some treatments was significantly correlated with the ratios of root and aerial biomass. Thus these ratios could be a useful index to estimate the efficiency of bioremediation of heavy metals.