Physiological of biochar and α-FeO nanoparticles as amendments of Cd accumulation and toxicity toward muskmelon grown in pots.

Background: Due to the severe cadmium (Cd) pollution of farmland soil, effective measures need to be taken to reduce the Cd content in agricultural products. In this study, we added α-FeO nanoparticles (NPs) and biochar into Cd-contaminated soil to investigate physiological responses of muskmelon in the whole life cycle.

Results: The results showed that Cd caused adverse impacts on muskmelon (Cucumis melo) plants. For instance, the chlorophyll of muskmelon leaves in the Cd alone treatment was reduced by 8.07-32.34% in the four periods, relative to the control. The treatments with single amendment, α-FeO NPs or 1% biochar or 5% biochar, significantly reduced the soil available Cd content, but the co-exposure treatments (α-FeO NPs and biochar) had no impact on the soil available Cd content. All treatments could reduce the Cd content by 47.64-74.60% and increase the Fe content by 15.15-95.27% in fruits as compared to the Cd alone treatment. The KEGG enrichment results of different genes in different treatments indicated that single treatments could regulate genes related to anthocyanin biosynthesis, glutathione metabolism and MAPK signal transduction pathways to reduce the Cd toxicity.

Conclusions: Overall the combination of biochar and α-FeO NPs can alleviate Cd toxicity in muskmelon. The present study could provide new insights into Cd remediation in soil using α-FeO NPs and biochar as amendments.