Improvement of root architecture, Pb, Cu and Zn uptake, translocation and phytoremediation efficiency of barley ( <i>Hordeum vulgare</i> ) through the application of biochar and sheep manure

Mining soil is considered a serious source of metal contamination worldwide due to its translocation and accumulation in various plant parts, causing severe impacts on plant growth. Results indicated that biochar and manure improved barley root morphology compared to contaminated soil. Moreover, Pb and Cu were highly translocated to shoots. Regarding treatments, manure 10% and 20% increased the Pb accumulation in roots, while animal manure 20% and biochar 2.5% increased its accumulation in shoots. Using manure of 10%, 20%, and biochar 2.5% promoted the accumulation of Zn in roots (bioaccumulation factor: BAF_root≥1). According to the Dickson quality index and tolerance index, barley plants showed a high tolerance for metals in soil. Biochar and manure were effective in reducing the negative effects of metals such as Cd and Pb on barley plants. Moreover, helps to increase the accumulation of Zn and Cu in barley roots and shoots. Our findings provide insight into the potential of biochar and manure to enhance crop production under metal stress, leading to the assurance of food supply and sustainable agriculture under stressful conditions. However, future research is highly needed, focusing on a field scale and testing metals' long-term effects on crop productivity and grain accumulation in contaminated soil.