Biochar amendment reduces oxidative stress in lettuce grown under copper excess

The aim of the study was to understand whether biochar can alleviate oxidative stress in lettuce grown in a Cu-contaminated soil. The results showed that biochar added to the contaminated soil decreased the bioavailability of the metal. The lower soil-extractable metal level determined a decreased uptake of Cu by lettuce. Biochar amendment reduced H2O2 formation as well as cell membrane peroxidation compared to plants grown in the contaminated soil. Copper-treated lettuce evidenced an oxidative stress as shown by the decrease in the ascorbate pool (total and reduced) and the enhancement of ascorbate peroxidase activity. Biochar amendment restored both ascorbate and enzyme activity to the control levels. The non-contaminated soil amended with biochar alone did not show differences compared to the control soil. The results of the study suggest that biochar can contribute to protect plants against metal toxicity alleviating Cu-induced oxidative stress.