Nanopriming with Silicon Quantum Dots Strengthens Wheat Drought Tolerance through Physiological Regulation and Microbial Functions

Seed priming offers a promising approach to strengthening drought resilience in wheat. In this study, seeds were primed with silicon quantum dots (SiQDs) at concentrations of 0, 250, 500, 750, and 1000 mg L^-1. Under drought stress induced by 15% PEG-6000, 500 mg L^-1 SiQDs increased the level of germination by 18.2%. In a 30 day pot experiment conducted under drought conditions at 40% field capacity, 500 mg L^-1 SiQDs significantly enhanced shoot biomass (157.1%) and the relative water content (26.7%), reduced root malondialdehyde (24.7%), and increased root proline (76.7%) and soluble sugar (68.7%). 16S rRNA gene and metagenomic sequencing analyses revealed that SiQDs enriched Proteobacteria in the rhizosphere, including the genera <i>Sphingomonas</i>, <i>Lysobacter</i>, and <i>Variovorax</i>, and activated functional pathways associated with biofilm formation and bacterial colonization. These results demonstrate that SiQD priming enhances drought tolerance by improving plant physiological responses and modulating rhizosphere microbial communities.