Silicon Quantum Dot Seed Priming Combined with Arbuscular Mycorrhizal Fungi Enhances Wheat Drought Tolerance through Physiological and Microbiome Regulation

Abstract

Although silicon quantum dot (SiQD) seed priming and arbuscular mycorrhizal (AMF) fungal inoculation can individually alleviate drought stress, their combined effects and microbiome-associated processes remain unclear. Here, we investigated the effects of SiQD seed priming and AMF inoculation on wheat drought tolerance, plant physiology, and rhizosphere–hyphosphere bacterial communities. SiQDs increased AMF root colonization by 22.8%, and AMF inoculation enhanced shoot Si by 11.7%. Compared with either treatment, the combined treatment improved the leaf relative water content, photosynthetic rate, osmotic adjustment, and plant nitrogen and phosphorus contents under drought stress. The combined treatment also enhanced the rhizosphere microbial network stability and enriched Sphingomonas, Steroidobacter, and Limibaculum, which were positively related to nutrient acquisition and drought-related physiological traits. A core hyphosphere microbiome dominated by Sphingomonas and Steroidobacter was also detected. These findings suggest that SiQDs and AMF improve wheat drought tolerance by strengthening plant physiological performance, enhancing nutrient acquisition, and modulating rhizosphere–hyphosphere bacterial communities.