Toxic effects, uptake, and translocation of Cd and Pb in perennial ryegrass

Cadmium (Cd) and lead (Pb) are regarded as the most toxic environmental pollutants because they are a threat not only to plants, but also to humans. Better understanding of the growth response, uptake and translocation of Cd and Pb in perennial ryegrass (Lolium perenne L.) would be helpful to evaluate the role of this grass species as a potential candidate used for phyto-remediation. Perennial ryegrass seedlings were subjected to three Pb levels (0, 0.5, and 3.2 mM) for 6 days and three Cd levels (0, 0.2, and 0.5 mM) for 7 days in a walk-in growth room. The Cd and Pb reduced the normalized transpiration and growth rate. Greater amount of Cd and Pb accumulated in roots relative to shoots. The enrichment coefficient (EC) and translocation factor (TF) were greater in plants treated with Cd than those with Pb. The dose of Cd had no effect on EC and TF. However, the plants subjected to higher dose of Pb had a greater TF and a lower EC relative to that with lower dose of Pb. Meanwhile, removal rates were decreased when the doses of Pb and Cd increased. The results indicated that perennial ryegrass preferred Cd assimilation to Pb, and can be considered as one of the plant species which accumulate high levels of Cd and Pb.