Can phosphate compounds be used to reduce the plant uptake of Pb and resist the Pb stress in Pb-contaminated soils?

摘要

The effects of different phosphate-amendments on lead(Pb) uptake,the activities of superoxide dismutase(SOD) and the level of malondialdehyde(MDA) in cauliflower(Brassica oleracea L.) in contaminated soils with 2500,or 5000 mg P2O5/kg soil of hydroxyapatite(HA),phosphate rock(PR),single-superphosphate(SSP) and the mix of HA/SSP(HASSP) were evaluated in pot experiments.Results showed that the Pb concentrations in shoots and roots decreased by 18.3%-51.6% and 16.8%-57.3% among the treatments respectively compared to the control samples.The effciency order of these phosphate-amendments in reducing Pb uptake was as follows:HASSP≈ HA > SSP ≈ PR.With the addition of SSP,HA and the mix of HA/SSP,the SOD activity in shoot was reduced markedly(P < 0.05) compared with that in the control group.For example,the SOD activities in shoot by the treatments of HASSP,SSP,and HA in 5000 mg P2O5/kg were found to be only 51.3%,56.2%,and 56.7%,respectively.Similar effects were also observed on the level of MDA in the shoots with a decrease in 24.5%-56.3%.The results verified the inference that phosphate compounds could be used to reduce the plant uptake of Pb and resist the Pb stress in the plant vegetated in Pb-contaminated soils.