Ramie Outperforms Golden Buckwheat in Cd-Contaminated Farmland Phytoremediation in Southern China: Core Microbes, Plant Traits and Soil Properties

Remediation of cadmium (Cd) pollution has always been a persistent dilemma. In this study, a field-based experiment for two years was conducted in Cd-contaminated farmland between ramie (Ra) and golden buckwheat (Gb). This study indicated that Ra is more recommended as a Cd-remediating crop in southern China, because it has a higher Cd remediation capacity than Gb, with a 2.7-fold Cd absorption over two years. Zinc (Zn) showed consistent trend with total Cd and residual Cd in soil, an antagonistic effect was observed between Zn and soil Cd forms absorption, which modulated Cd bioavailability. A putative interaction involving Sphingomonas and the tissues of Ra’s bast and Gb’s leaves was detected, a process hypothesized to promote the upward translocation of cadmium (Cd) to aerial plant tissues. This study provides a basis for optimizing the phytoremediation practice of Cd-contaminated farmland soil and screening of remediation plants.