Pig bedding biochar enhances the Cd extraction capacity of Perilla frutescens by mitigating the toxicity of Cd-contaminated soil

Abstract

Pig bedding biochar (PBBC) and Cd-enriched Perilla frutescens were used for joint remediation of Cd-contaminated soil. Cd-contaminated soil was treated with different concentration of PBBC. The physiological and biochemical indicators of P. frutescens was evaluated under different Cd stress, including biomass, antioxidant system. Meanwhile Cd bioavailability, enzyme activity and nutrient bioavailability of the soil were monitored. Results revealed that PBBC at 1 % and 5 % levels led to decreased diethylenetriaminepentaacetic acid-extractable Cd (DTPA-Cd) content in soil by 19.09 %-20.05 % and 30.10 %-47.08 %, respectively. Moreover, PBBC promoted the transformation of exchangeable Cd (EXC-Cd) into a more stable form, enhanced soil enzymes (peroxidase, acid phosphatase, urease, and sucrase) activities, and alleviated P. frutescens 's oxidative stress. PBBC increased its biomass, consequently enhancing Cd accumulation in the plant's, thereby improving Phytoextraction rate (PER). 1 % PBBC showed the best effect, with a total biomass increased 21.42 %-26.94 %, PER was enhanced by 39.83 %-54.82 %. This study justifies that the combining PBBC with P. frutescens enhances Cd removal from soil, making the PBBC-P. frutescens a promising choice for treating Cd-polluted soil.