Biochar improves the yield and quality of Erigeron breviscapus in heavily cadmium-polluted soil

Simultaneous utilization and remediation of soils contaminated with cadmium (Cd) is a propitious and economically beneficial task. Here, we undertook a pot experiment with biochar application at four rates (0, 5, 10, and 15%, denoted as BC0, BC5, BC10, and BC15, respectively) with the addition of 0.1% Cd, along with a control without Cd and biochar addition (CK). Erigeron breviscapus , a raw medicinal material used to extract scutellarin, was grown in all treatments to investigate a new method of utilizing and remediating heavily Cd-contaminated soil. The results showed that the high Cd-contaminated soil decreased the yield and scutellarin content of E. breviscapus by 33.6% and 70.8%, respectively. Compared to BC0, the yield and scutellarin content in BC15 increased by 24.7% and 312.0%, respectively. Biochar application (BC5, BC10, BC15) changed the soil Cd speciation and reduced the soil available Cd content by 17.4–121.8% and plant Cd content by 26.4–42.6% compared with BC0. However, chlorophyll content, catalase (CAT) activity, and acquisition of N, Fe and Cu of E. breviscapus increased in BC5, BC10, and BC15 compared to BC0. Additionally, the mitigation effect of Cd toxicity enhanced with increasing biochar application, and 15% biochar application resulted in the highest yield and scutellarin content of E. breviscapus. This study highlights the importance of biochar for improving the Cd adaptability of E. breviscapus and provides a reference for the simultaneous utilization and remediation of heavily Cd-contaminated soil.