Intercropping of Euonymus japonicus with Photinia × fraseri Improves Phytoremediation Efficiency in Cd/Cu/Zn Contaminated Field

SIMPLE SUMMARY: Intercropping of different greening plant species is a regular management practice in landscape engineering. However, how this approach works on the remediation of heavy metal soil is not fully known. Here, the effect of intercropping two greening species, Euonymus japonicus and Photinia × fraseri on phytoremediation efficiency was studied in a Cd/Cu/Zn-contaminated field. This study provides (1) a feasible biotechnique for improving phytoremediation efficiency using greening plants and (2) a more practical work for multiple HM-polluted soil than research on single-polluted soil. ABSTRACT: Intercropping plants for phytoremediation is a promising strategy in heavy metal-polluted soils. In this study, two typical greening plant species, Euonymus japonicus (E. japonicus) and Photinia × fraseri (P. × fraseri), were intercropped in a Cd/Cu/Zn-contaminated field. The phytoremediation efficiency was investigated by measuring the plant biomass, metal concentration, and mycorrhizal colonisation, as well as the effects on soil properties, including soil pH; soil total N; and available N, P, K, Cd, Cu, and Zn. The results showed that, compared with the monoculture system, intercropping significantly lowered the available Cd, Cu, and Zn contents, significantly improved the total and available N contents in rhizosphere soils of both plant species, and increased the hyphae colonisation rate of P. × fraseri. In both plants, intercropping significantly improved the total plant biomass. Furthermore, the concentrations Zn and Cd in the root of E. japonicus and Cu concentration in the root of P. × fraseri were enhanced by 58.16%, 107.74%, and 20.57%, respectively. Intercropping resulted in plants accumulating higher amounts of Cd, Cu, and Zn. This was particularly evident in the total amount of Cd in E. japonicus, which was 2.2 times greater than that in the monoculture system. Therefore, this study provides a feasible technique for improving phytoremediation efficiency using greening plants.