Biochar mediated alleviation of cadmium stress in crop plants

• Biochar mitigates Cd toxicity, improving soil and plant health. • Reduces Cd uptake, enhances photosynthesis, and boosts antioxidant defense. • Improves water and nutrient uptake, supporting plant growth under stress. • Eco-friendly solution for remediating Cd-contaminated soils and food security. • Reviews mechanisms, advancements, and gaps in using biochar for Cd remediation. Cadmium (Cd) toxicity is a serious challenge to food productivity and human health. This challenge is exacerbated by the continuous release of industrial effluents and chemical fertilizers. Cadmium toxicity severely impairs plant functioning, cause oxidative damage, disrupt nutrient and water uptake, and reduce photosynthetic efficiency, leading to a reduction in plant growth. Biochar has demonstrated considerable potential in mitigating Cd toxicity, offering numerous benefits such as reducing Cd uptake, improving water and nutrients uptake, photosynthesis, boosting antioxidant defense, maintaining hormonal balance, and influencing gene expression. Biochar also improves soil microbial activities, nutrient uptake, and decreases the availability of Cd by forming Cd-OM complexes and increasing Cd immobilization and adsorption. This review discusses (i) the behavior and deposition of Cd on land and water surfaces, along with its uptake and translocation mechanisms in plants; (ii) the challenges to food security and human health posed by Cd-contaminated soils, highlighting the critical link between soil quality and sustainable food systems; (iii) the mechanisms by which biochar application mitigates Cd toxicity in soil-plant systems, including its potential to enhance plant physiological functioning and regulate soil physicochemical and biological properties, as well as nutrient availability; and (iv) the potential of biochar to reduce health risks associated with Cd exposure. Overall, this review provides a foundation for the development of eco-friendly strategies to mitigate Cd toxicity and promote safer and sustainable crop production.