Effect of fertilizers on the Cd uptake of two sedum species (Sedum spectabile Boreau and Sedum aizoon L.) as potential Cd accumulators

A pot experiment was conducted to investigate the potential for cadmium (Cd) phytoextraction of two sedum species (Sedum spectabile Boreau and S. aizoon L.), as well as the effects of N, NP, and NPK fertilizers on the Cd uptake of the two sedum species grown in soil contaminated with 2.2 mg·kg−1 Cd for 60 d. Results showed that the Cd concentrations in S. spectabile and S. aizoon tissues ranged within 7.49-14.4 mg·kg−1 in leaves, 5.48-9.69 mg·kg−1 in stems, and 2.38-6.06 mg·kg−1 in roots. Moreover, the biomass and Cd concentrations of S. spectabile tissues were significantly higher than those of S. aizoon, thereby leading to a higher Cd uptake in shoots and bioconcentration factor than S. aizoon. N and NP fertilizers had limited effects on the biomass and Cd phytoextraction efficiency of both sedum species. NPK fertilizers significantly increased the S. spectabile biomass by 21.2% compared with the control (p < 0.05) and greatly improved Cd concentrations in S. spectabile stems by 24.4% and 25.4% compared with N and NP fertilizers (p < 0.05), respectively. All these findings indicated that S. spectabile can be used to phytoremediate Cd-contaminated soil, and that NPK fertilizers can improve phytoextraction efficiency. Further studies are warranted to optimize fertilizer-combination ratios and elucidate interaction mechanisms among fertilizers in field experiments.