Nanoparticle-mediated drought resilience in cereal crops from physiological modulation to sustainable agronomic translation

Nanotechnology offers transformative potential for mitigating drought stress in cereal crops, yet translation from controlled environments to field applications remains constrained by inconsistent outcomes, limited mechanistic understanding, and insufficient environmental risk assessment. This review critically synthesizes recent advances in nanoparticle (NP)-mediated drought resilience across wheat (Triticum aestivum), maize (Zea mays), and rice (Oryza sativa), with emphasis on mechanistic dissection of NP-plant interactions, species-specific responses, and translational pathways. We systematically evaluate metal/metal oxide, silicon-based, carbon-based, and polymer/bio-based NPs, distinguishing where evidence permits between particle-specific surface effects and ion-derived contributions. Quantitative concentration thresholds for optimal drought mitigation and toxicity limits are provided, revealing narrow hormetic windows that vary markedly with crop physiology, root architecture, and silicon uptake capacity. Mechanistically, NPs modulate interconnected networks governing water relations, photosynthetic efficiency, antioxidant defense, osmotic adjustment, and phytohormonal signaling, with transcriptomic evidence indicating reprogramming of stress-responsive genes. We propose a trait-based translational framework linking NP physicochemical properties to quantifiable phenotypic targets with integrated environmental risk gates addressing NP persistence, dissolution kinetics, soil microbial impacts, and biosafety. Critical research gaps include: (i) rigorous separation of particle-specific from ionic mechanisms through appropriate controls; (ii) crop- and stress-specific dose calibration; (iii) long-term field validation under climate-change relevant drought scenarios; and (iv) ecotoxicological assessment in dryland agroecosystems. This review provides a mechanistic roadmap for developing sustainable, field-applicable nano-enabled strategies that balance agronomic benefits against ecological safety in climate-resilient cereal production.