Effect of Phosphorus Application on Eggplant Cadmium Accumulation and Soil Cadmium Morphology

Soil cadmium (Cd) contamination affects human health, and the application of phosphorus (P) fertilizer can inhibit the toxic effects of Cd; however, the effects of different P fertilizers on Cd accumulation in calcareous soils are unknown. To address this point, this paper used a pot experiment with four P fertilizer types (monoammonium phosphate (MAP), superphosphate (SSP), diammonium phosphate (DAP), and dicalcium phosphate (DCP)) and four P fertilizer levels (0, 0.15, 0.25, and 0.35 g kg-1, P per kg of soil). The effects of P application on the biomass of eggplant, Cd content, bioconcentration factors, translocation factor, yield quality, and soil Cd morphology changes in a Cd-contaminated environment were explored. Applying 0.35 g kg-1 of DCP significantly increased eggplant biomass while reducing Cd accumulation, concentration, and transport within eggplants under Cd contamination. The P fertilizer changed the distribution of soil Cd morphology. A redundancy analysis identified Cd content in the residual and Fe/Mn oxides-bound states as the primary factors influencing Cd levels in plants. In summary, the application of 0.35 g kg-1 DCP proved most efficient in mitigating Cd accumulation in eggplants under Cd-induced stress conditions.