Biochar improves Pb and Cd-induced stress in mung bean (Vigna radiata L. Wilczek)

Lead (Pb) and cadmium (Cd) are trace elements known for their potential harm to plants. Their toxicity can lead to increased oxidative harm, disturbance in plant metabolism, and deformation in plant structure. Biochar (BC), when utilized as a soil amendment, demonstrates effectiveness in mitigating the toxicity of these heavy metals in polluted soils. To investigate the effects of BC made from sunflower residues on reducing Pb- and Cd-induced stresses in mung bean (Vigna radiata L. Wilczek), a factorial experiment was conducted based on a completely randomized design with three replications in greenhouse conditions. The factors included Pb at three levels (0, 100, and 200 mg kg^-1 as Pb (NO₃)₂), Cd at three levels (0, 10, and 20 mg kg^-1 soil as Cd (NO₃)₂), and BC at three levels (0, 1, and 3 % by weight). The results showed that Pb and Cd-induced stresses reduced all growth characteristics, such as shoot and root dry weights and the number of active root nodules. Maximum soluble sugars (0.46 mg kg^-1) and proline content (44.7 µmol g^-1) were observed in 200 mg kg^-1 of Pb and 20 mg kg^-1 of Cd treatment without BC. Also, the application of BC reduced the concentration of Pb and Cd in the shoot by 19.1 % and 13.8 %, respectively, and increased all growth traits. Therefore, the application of BC made from sunflower residues is recommended as a promising and environmentally friendly approach to improves Pb and Cd-induced stress in mung beans.