Engineered biochar nanocomposites: integrating nanotechnology with carbon-based materials to enhance plant resilience against biotic and abiotic stresses

Climate change intensifies plant stress factors and threatens global food security and therefore demands sustainable land management practices. Engineered biochar nanocomposites (EBNCs) are the synergistic combination of nanotechnology to improve carbon sequestration and sustainable approach for the precise functionality of biochar (BC) to amend soil properties. This comprehensive review examines the design, fabrication, and mechanisms of EBNCs to mitigate both biotic and abiotic stresses in plants. We analyze recent advances in EBNC synthesis through physical, chemical, and biological integration routes for incorporating metal/metal oxide nanoparticles (NPs) i.e., Ag, Fe, ZnO, TiO 2 , and graphene into BC matrices. EBNCs induced mechanisms of stress alleviation are enhanced water retention, ion homeostasis, heavy metal (HM) immobilization, antimicrobial activity, induced systemic resistance (ISR), and scavenging reactive oxygen species (ROS). The applications of EBNCs significantly improve crop performance under drought, salinity, HM contamination, or pathogen stress. However, production costs, environmental trade-offs, potential toxicity, and regulatory policies are research gaps and require further careful consideration. Future research should focus on developing smart, stimuli-responsive EBNCs with controlled-release properties, integration of omics and artificial intelligence tools for optimized formulations, and circular economic approaches. EBNCs are increasingly recognized as multifunctional materials with potential applications in climate-resilient and sustainable agriculture.