Impact of Hydrogen-Enriched Solution Irrigation on Grain Yield and Nutritional Quality of Sweet Corn

Simultaneously improving the yield and, in particular, the nutritional quality of sweet corn (Zea mays L. saccharata), one of the most important cereal fresh foods worldwide, remains a major challenge. Here, we demonstrated that compared to control groups, hydrogen-enriched water (HEW) irrigation significantly improved agronomic performance, increasing kernel number (~10.55%) and ear length (~5.73%) while notably reducing barren tip length by about 60.73%. Regarding nutritional quality, HEW-treated kernels exhibited remarkable increases in soluble protein (~61.53%), total soluble sugars (~31.10%), vitamin C (~28.31%), total phenolics (~21.06%), and flavonoids (~40.56%). Micronutrients were also enhanced, such as zinc (~96.82%), iron (~51.70%), and manganese levels (~40.37%). HEW effectively modulated the expression of sugar metabolism-related genes. Specifically, the coordinated upregulation of key genes, such as ZmSUS1 (~3.8 fold), ZmINCW2 (~1.9 fold), and ZmHXK1 (~1.6 fold), might contribute to the enhanced accumulation of sucrose (~11.79%), glucose (~6.21%), and fructose (~26.50%). Starch biosynthesis was also promoted. The improved sugar–acid ratio indicated enhanced taste quality. Importantly, representative key antioxidant genes (ZmSOD2/4, ZmPOD1/2, and ZmCAT1/3) as well as corresponding enzymatic activities in kernels were stimulated, which was negatively associated with lipid peroxidation. Overall, these results indicate that HEW irrigation is a promising, eco-friendly strategy that can be efficiently used to improve sweet corn yield and nutritional value.