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 Sphingomonas, Lysobacter, and Variovorax, 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.