<p>Numerous studies have shown that Se significantly affects plant physiological characteristics and organic material accumulation. However, limited understanding of the effects of Se on plants and their organic forms has hindered the development of Se-rich food production. To determine the optimal application rates of Se for improving sweet potato (<i>Ipomoea batatas (L.) Lam</i>) quality, field trials were conducted with foliar Se applications. The yield peaked at 34,669 kg hm⁻² with the 0.8 mg L⁻¹ Se, and application of 10 mg L⁻¹ Se significantly increased photosynthesis (Pn) while slightly decreasing leaf chlorophyll content. The contents of polysaccharides and proteins increased with certain Se applications, and the highest Se concentrations in the polysaccharide and protein fractions of tubers were observed in the 10&#xa0;mg L⁻¹ treatment. Furthermore, Se increased the contents of the seleno-amino acids Se-Met, Se-MeSeCys, and Se-Cys₂in sweet potato, with Se-Met being the predominant form, peaking before decreasing as Se fertilizer concentration increased. Overall, Se enrichment followed the pattern: leaf &gt; stem &gt; tuber. Hence, this study provides valuable insights into the optimal Se application rates for enhancing the nutritional quality and yield of sweet potatoes, guiding agricultural practices for better crop management.</p>