Research progress on the mechanism of nanoparticles in alleviating crop drought stress

Under the background of global climate change and water scarcity, drought has become one of the major abiotic factors affecting crop growth and yields, thereby posing a serious threat to global food security. In recent years, nanoparticles have demonstrated significant potential for synergistically enhancing the drought resistance of crops due to their unique physicochemical properties. Therefore, this paper reviews the related studies in recent years to summarize the effects of drought stress on plant physiology, biochemistry, and morphology, as well as the response strategies of plants. Drought stress exerts adverse effects on plant development, as well as on physiological and metabolic pathways, to interfere with cell membranes, antioxidant activity, photosynthetic systems, and nutrient absorption, thereby affecting plant growth and crop productivity. In response, plants have evolved adaptive mechanisms such as drought escape, drought avoidance, and drought tolerance. The strategic application of nanoparticles under drought conditions can effectively bolster crop resilience, subsequently elevating crop yields and quality. This review systematically summarizes the regulatory mechanisms of nanoparticles on the drought resistance of crops. These mechanisms encompass reinforcing the antioxidant defense system, optimizing photosynthetic performance, facilitating osmotic adjustment, modulating phytohormone balance and associated gene expression, and preserving nutrient homeostasis. Furthermore, this review discusses the influences of the properties of nanoparticles on the drought resistance of crops. In terms of the types of nanoparticles, ZnO NPs exhibited remarkable plant growth-promoting effects under drought stress; in terms of application concentrations, the application concentration of NPs under drought conditions presents a quadratic parabolic trend on the biomass of the aboveground parts of crops, which decreases at low application concentrations and increases at high application concentrations; in terms of application methods, foliar spraying and soil application of NPs are the most effective for crop growth under drought conditions. In addition, this article points out the current application status and challenges of nanoparticles in alleviating drought stress. Future research on nanomaterials in the drought resistance of crops can focus on issues such as the standardization of precise application, optimization of nanodesign components, deep-level signal regulation of drought responses, integration of multi-omics and gene editing technologies to decipher mechanisms, and adaptability to multiple stresses. On the basis of eliminating the biological toxicity and eco-environmental risks of nanoparticles, it is necessary to promote the efficient and sustainable application of nanoparticles in enhancing drought resistance. The paper aims to explore the role of nanoparticles in alleviating the drought stress of crops, thereby providing theoretical guidance for the research and application of nano-fertilizers, and promoting sustainable agricultural development and ensuring global food security.