Integrated fertilization regimes boost heavy metals accumulation and biomass of sedum alfredii hance

Abstract

The hyperaccumulator Sedum alfredii Hance (S. alfredii) may be employed for zinc (Zn) and cadmium (Cd)-polluted soil remediation. However, the low phytoremediation efficiency, related to the low biomass production, limits its use with that purpose. In this experiment, nitrogen (N), phosphorus (P), and potassium (K) fertilizers, and organicmanurewereappliedtoinvestigatethephytoremediationabilityofS. alfredii. Hydroponicandpotexperi-ments were conducted using Zn-Cd polluted soil. The hydroponic experiment indicated that appropriate fertilizer application could increase (p < 0.05) the amount of accumulated Zn and Cd in S. alfredii. When N supply ranged from 0.5 to 2.5 mmol L−1, it could improve growth and accumulation of Zn and Cd in whole plants of S. alfredii. The 1 mmol L-1 N was an optimal N dosage for shoot biomass production and Cd accumulation in shoots, while the 2.5 mmol L-1 was an optimal N dosage for Zn accumulation in shoots. Both low (<0.05 mmol L-1) and high (>0.8 mmol L-1) P supply decreased growth, and Zn/Cd accumulation in whole plants of the studied species. The 0.1 mmol L-1 P was an optimal dosage for S. alfredii biomass production and Zn/Cd accumulation in shoots. The supply levels within the range from 0.3 to 1 mmol L-1 K could significantly improve the biomass production of S. alfredii and its capability to accumulate Zn and Cd in the biomass. The 0.5 mmol L-1 K was an optimal dosage for the whole biomass production and Zn accumulation in shoots, while the 1 mmol L-1 was an optimal K dosage for Zn accumulation in shoots, which was 17.2% higher than the control. Moreover, the soil pot experiment showed that the combination of organic (fermented manure) and inorganic fertilizers made significant effects on the Zn and Cd-polluted soil remediation by S. alfredii. These effects varied, however, with the application of different proportions of N, P, K and organic matter. The Zn accumulation by S. alfredii reached the highest efficiency ability under the highest fertilizer mixing rate (N: 50 mg kg-1,P:40mgkg-1,K:100mgkg-1, organic matter: 1%). Even more, S. alfredii showed the strongest ability to accumulate Cd with a lower fertilizer mixing rate (N: 25mg kg-1,P:20mgkg-1,K: 50 mg kg-1, organic matter: 0.5%).