Physiology combined with transcriptomics and 16S rRNA profiling reveals the regulation of winter wheat's adaptability to saline-alkali land by foliar spraying of selenium nanoparticles

The effects of nano-fertilizers on crop antioxidant properties and photosynthetic characteristics are a focus in agricultural research. This study aimed to explore how selenium nanoparticles (SeNPs) influence wheat photosynthesis, stress tolerance, and grain quality under hydroponic and field conditions, by integrating physiological indicators with transcriptomics and bacterial community profiles. Hydroponic wheat received 5 treatments: CK (0 M Se), T1 (0.1 M Se), T2 (0.2 M Se), T3 (0.3 M Se), T4 (0.4 M Se). Field wheat had 5 treatments: CK (0 g Se·ha −1 ), T1 (3.75 g Se·ha −1 ), T2 (7.50 g Se·ha −1 ), T3 (15.00 g Se·ha −1 ), T4 (30.00 g Se·ha −1 ). We conducted multiple analyses, including physiological assessments, transcriptomic studies, and bacterial 16S rRNA profiling. SeNPs boosted wheat photosynthesis and antioxidant capacity. Transcriptomics identified SeNP-induced DEGs linked to zinc transport, lipid binding, flavonoid biosynthesis, and metabolic pathways (e.g., starch-sucrose metabolism). SeNPs increased rhizosphere microbial richness and metabolic pathway abundance. Field T3 (15 g Se·ha −1 ) enhanced grain Se accumulation, protein content, and balanced Se biofortification with agronomic traits. Foliar application of SeNPs significantly promotes the growth, stress resistance, and grain quality of wheat grown in saline-alkali soil, among which the field T3 treatment is preferable for wheat Se biofortification in such soil conditions.Overall, this work uncovers SeNPs’ regulatory mechanisms in wheat, lays a theoretical and practical basis for nutrient-enriched wheat cultivation in saline-alkali soils, and highlights key priorities for subsequent studies.