Phytoextraction of zinc by oat (Avena sativa), barley (Hordeum vulgare), and Indian mustard (Brassica juncea)

The success of phytoremediation hinges on the selection of plant species and soil amendments that maximize contaminant removal. Indian mustard (Brassica juncea) has been shown to be effective in phytoextracting Zn, particularly after the synthetic chelate EDTA has been applied to the soil. However, the effectiveness of grass species for phytoremediation has not been addressed in great detail. A hydroponic screening of 22 grass species indicated that oat (Avena sativa) and barley (Hordeum vulgare) tolerated the high Cu, Cd, and Zn concentrations present in the solution and also accumulated elevated concentrations of these metals in the plant shoots. A hydroponic experiment comparing these two grasses to Indian mustard indicated that, although shoot Zn concentrations were greater for Indian mustard, the grasses were considerably more tolerant. A pot experiment conducted using a Zn-contaminated soil showed that the addition of EDTA to the soil significantly increased Zn accumulation by B. juncea but not oat or barley. Nevertheless, barley accumulated >2 mg of Zn plant(-1), 2-4 times more Zn than what was observed in Indian mustard in the presence of EDTA. The results of this experiment suggest that barley has a phytoremediation potential equal to, if not greater than, that for B. juncea.