Sugars will eventually be exported transporters (SWEETs) are essential transmembrane proteins involved in plant growth, stress responses, and plant–pathogen interactions. Despite their importance, systematic studies on SWEETs in blueberries (Vaccinium corymbosum L.) are limited. Blueberries are recognized for their rapid growth and the significant impact of sugar content on fruit flavor, yet the role of the SWEET gene family in sugar accumulation during fruit development remains unclear. In this study, 23 SWEET genes were identified in blueberry, and their phylogenetic relationships, duplication events, gene structures, cis-regulatory elements, and expression profiles were systematically analyzed. The VcSWEET gene family was classified into four clades. Structural and motif analysis revealed conserved exon–intron organization within each clade. RT-qPCR analysis showed widespread expression of VcSWEETs across various tissues and developmental stages, correlating with promoter cis-elements. VcSWEET6a, in particular, was specifically expressed in fruit and showed reduced expression during fruit maturation. Subcellular localization indicated that VcSWEET6a is located in the endoplasmic reticulum. Functional assays in yeast confirmed its role in glucose and fructose uptake, with transport activity inhibited at higher sugar concentrations. Overexpression of VcSWEET6a in blueberries resulted in reduced sugar accumulation. These findings offer valuable insights into the role of VcSWEETs in blueberry sugar metabolism.

Nitrogen (N) is the most critical element influencing plant growth and development. Different plant species exhibit varying preferences for different N forms. In order to identify an appropriate nutrient solution N formula for optimizing blueberry substrate cultivation, we investigated the effects of seven different NH₄⁺-N/NO₃⁻-N ratios on the growth characteristics, photosynthetic physiology, mineral element content, enzymes related to N metabolism, and fruit quality, with ‘F32’ used as the experimental material and water served as controls. The results demonstrated that both the aboveground and belowground parts of blueberry plants exhibited enhanced growth when NH₄⁺-N was used as the primary N source in the nutrient solution, compared to single NH₄⁺-N or a high NO₃⁻-N ratio. The most significant growth promotion occurred when the NH₄⁺-N to NO₃⁻-N ratio was 7:3. When NH₄⁺-N and NO₃⁻-N are concurrently supplied in the nutrient solution, the processes of NO₃⁻ reduction, the GS-GOGAT cycle, and NH₄⁺ assimilation are significantly enhanced during nitrogen metabolism. Thereby, providing a theoretical foundation for optimizing nutrient solution management in substrate-cultivated blueberry.