Effect of phosphorus fertilizer on phytoextraction using Ricinus communis L. in Cu and Cd co-contaminated soil

Mining activities have led to Cu and Cd contaminated of surrounding agricultural soil. To decrease the Cu and Cd accumulation in crops, the Ricinus communis L. (castor) has been used for phytoremediation. A pot experiment was served to investigate the effect of phosphate fertilizer (Ca(H2PO4)(2)) on the growth and Cu/Cd uptake of castor in contaminated soil. The results showed that the application of P fertilizer improved the leaf cell morphology, decreased the malonaldehyde (MDA) content of castor leaves, and increased the plant biomass (28.2-34.2%). Besides, phosphate fertilizer still facilitated accumulation Cu and Cd by castor. The addition of phosphate fertilizer increased the contents of Cu in the root of castor, improved the bioconcentration factor (BCF) of Cu, and observably enhanced the accumulation of Cu (up to 201 mu g/plant) in castor. Applying phosphorus increased the percentage of residual Cd, diminished the percentage of acid extractable Cd in soil, and the accumulation of Cd in castor was not significantly increased. These results suggest that phosphorus alleviated the stress of heavy metals on castor leaves and enhanced the accumulation of Cu and Cd in castor by promoting the growth of castor. Novelty statement Applying phosphate fertilizer effectively alleviated the stress of heavy metals on castor and significantly increased the biomass of castor. The reason of applying phosphorus enhanced the castor uptake Cu and Cd was that phosphorus promoted the growth of castor. Applying phosphorus markedly increased the percentage of residual Cd but diminished the percentage of acid extractable Cd in soil.

Automated summary

Mining activities have resulted in Cu and Cd contamination in the surrounding agricultural soil. To mitigate the accumulation of Cu and Cd in crops, the use of Ricinus communis L. (castor) for phytoremediation has been explored. A pot experiment was conducted to assess the impact of phosphate fertilizer (Ca(H2PO4)(2)) on the growth and Cu/Cd uptake of castor in contaminated soil. The findings demonstrate that the application of P fertilizer enhanced leaf cell morphology, reduced malonaldehyde (MDA) content in castor leaves, and increased plant biomass. Additionally, phosphate fertilizer facilitated the accumulation of Cu and Cd by castor. The addition of phosphate fertilizer increased Cu content in castor roots, improved the bioconcentration factor (BCF) of Cu, and significantly enhanced Cu accumulation in castor. Phosphorus application also increased the percentage of residual Cd in soil, while reducing the percentage of acid extractable Cd. However, Cd accumulation in castor was not significantly affected. These results highlight the role of phosphorus in alleviating heavy metal stress on castor and promoting its growth, subsequently enhancing Cu and Cd accumulation in the plant. Novelty statement：The application of phosphate fertilizer effectively alleviated heavy metal stress on castor and greatly increased its biomass. The promotion of Cu and Cd uptake in castor by phosphorus can be attributed to its positive effect on plant growth. Phosphorus application significantly increased the percentage of residual Cd in soil, but decreased the percentage of acid extractable Cd.