Effects of biochar on growth of Asian lotus (Nelumbo nucifera Gaertn.) and cadmium uptake in artificially cadmium-polluted water

- Effects of biochar on plant growth and cadmium accumulation in lotus were evaluated.
- Plant biomass significantly increased with biochar proportion in soil mix.
- Cadmium content in plant tissues significantly decreased with adding biochar.
- Impacts of biochar on plant physiological characteristics were not very clear.
- Biochar has big potential in green agriculture and cadmium pollution remediation.

To further understand the benefits of biochar in crop production and remediation of heavy metal pollution, the effects of biochar on the growth of Nelumbo nucifera 'Taikong 36' and cadmium (Cd) accumulation in plant tissues were evaluated in the artificially Cd-polluted water-soil. The results showed that plant biomass significantly increased with the proportion (0-32%) of biochar in the soil mix. However, the impacts of biochar on plant physiological indicators were not clear. Compared with the control, the addition of 32% biochar significantly decreased Cd content in rhizomes, petioles, and leaves of N. nucifera 'Taikong 36' by 69, 81, 55%, respectively. Correspondingly, the bioaccumulation coefficient of Cd was reduced, by a maximum of 71%, and the Cd transfer coefficient from underground to aboveground tissues increased up to 1.3 fold. The bioaccumulation coefficient of Cd in rhizomes was significantly lower than that of leaves, indicating that biochar mitigated the effect of heavy metal ions and reduced the accumulation of Cd in the edible parts of lotus. Therefore, biochar has potential in green agriculture production and remediation of heavy-metal polluted water and soil due to its positive effects: improving plant growth and reducing heavy metal pollution.