Potential of four forage grasses in remediation of Cd and Zn contaminated soils

A pot experiment was conducted in a greenhouse to evaluate the phytoremediation abilities of four forage grasses with respect to soil Cd and Zn pollution. High Cd pollution significantly increased the biomass of Pennisetum americanum (L.) Leeke × Pennisetum purpureum Schumach, showed no effect on Silphium perfoliatum Linn and significantly decreased biomass of Paspalum atratum cv. Reyan No. 11 and Stylosanthes guianensis cv. Reyan II. High Zn pollution significantly decreased biomass of all grasses. Shoot Cd extraction amounts were 624, 179, 21 and 15 μg/plant for P. americanum × P. purpureum, P. atratum, S. guianensis and S. perfoliatum respectively at soil Cd concentration of 8 mg/kg. The shoot Zn extraction amount for P. americanum × P. purpureum was 8189 μg/plant while the other three grasses were severely intoxicated at the soil Zn concentration of 600 mg/kg. P. americanum × P. purpureum and P. atratum could be useful for phytoextraction of either or both Cd and Zn pollution; S. perfoliatum could be regarded as a candidate species for phytostabilization of Cd contamination; while S. guianensis had no remediation capability.