GSNO-functionalized hydroxyapatite nanofertilizer for prolonged delivery, detoxification, and yield improvement in maize.

The agricultural use of nitric oxide (NO) is restricted by the instability of conventional donors. Here, we develop a facile one-pot method to immobilize S-nitrosoglutathione (GSNO) onto humic acid-coated hydroxyapatite nanoparticles (GSNO-HAs-Fe-HAP NPs). Particle characterization confirms favorable properties for agricultural applications, including prolonged NO release (>6 days) and the mitigation of maize cadmium (Cd) stress. Release test verifies the corelease of humic acid and crop nutrients, while confocal microscopy demonstrates robust NP uptake in maize. Under Cd stress, GSNO-HAs-Fe-HAP outperforms commercial NPK fertilizer, improving photosynthetic efficiency and agronomic traits, reducing grain Cd accumulation by 86%, and upregulating phytochelatins, S-nitrosothiols, and metal transporters (ZmPCR, ZmABCC1, and ZmABCG40). The NP composite reduces ROS accumulation and enhances antioxidant enzyme activity, osmolytes, phenolics, flavonoids, and stress phytohormones. Furthermore, NPs significantly improve soil health parameters and the rhizosphere microbiome. Thus, GSNO-HAs-Fe-HAP is a promising nanofertilizer for prolonged NO delivery and Cd stress mitigation.