Mercapto-functionalized palygorskite modified the growth of Ligusticum Chuanxiong and restrained the Cd migration in the soil-plant system

Ligusticum Chuanxiong is an essential medicinal and edible plant, but it is highly susceptible to the enrichment of soil Cadmium (Cd), which seriously affects its medical safety. However, the control of Cd uptake by Ligusticum Chuanxiong is little reported. In this study, we reported that a green Mercapto-functionalized palygorskite (MPAL) effectively promoted Ligusticum Chuanxiong growth, and restrained the Cd uptake by Ligusticum Chuanxiong both in the mildly contaminated soil (M-Soil) and severely contaminated soil (S-Soil). The experimental results demonstrated that the application of MPAL significantly increased the biomass and antioxidant enzyme activity of Ligusticum Chuanxiong. In the M-Soil, the Cd content in the roots, stems, and leaves of Ligusticum Chuanxiong decreased markedly by 82.46-86.66%, 64.17-71.73%, and 64.94-76.66%, respectively, after the MPAL treatment. In the S-Soil, MPAL application decreased the Cd content in roots, stems, and leaves by 89.43-98.92%, 24.19-86.22%, and 67.14-77.90%, respectively. Based on Diethylenetriamine Pentaacetic Acid (DTPA) extraction, the immobilization efficiency of MPAL for Cd in soils ranged from 22.01% to 77.04%. Additionally, the HOAc extractable Cd was transformed into reducible and oxidizable fractions. Furthermore, MPAL enhanced the activities of soil alkaline phosphatase, and urease, but decreased sucrase activity. Environmental toxicological analysis indicated that MPAL reduced the potential ecological risk of Cd in the soil. These findings revealed that MPAL can effectively reduce Cd accumulation in Ligusticum Chuanxiong and promote plant growth, suggesting its potential as a viable amendment for remediating Cd-contaminated soils.