{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T00:41:41Z","timestamp":1792024901904,"version":"4.4.0"},"reference-count":48,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T00:00:00Z","timestamp":1786665600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005908","name":"Bundesministerium f\u00fcr Ern\u00e4hrung und Landwirtschaft","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100005908","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Plant Sci."],"abstract":"<jats:p>\n                    Onion bulb quality is largely defined by non-structural carbohydrates, phenolic antioxidants, and sulfur-containing flavor precursors, yet integrative evidence on how these domains respond to nitrogen imbalance under controlled conditions remains limited. A pot experiment applied four ammonium nitrate levels (N1\u2013N4; 0.5\u20134.0 g NH\n                    <jats:sub>4<\/jats:sub>\n                    NO\n                    <jats:sub>3<\/jats:sub>\n                    per pot) to two contrasting onion varieties (hybrid Hytech F1 and landrace Birnenf\u00f6rmige). Bulb morphology and quality traits were quantified alongside tissue elemental C:N ratios and a targeted trait\u2013metabolite matrix covering carbohydrates, amino acids (including Allium-specific alk(en)yl cysteine sulfoxides, ACSOs), organic acids and other primary metabolites, as well as flavonoids, driven by higher dry matter and fructan-rich reserve pools in Birnenf\u00f6rmige versus higher soluble sugars and nitrogen-status metabolites in Hytech. Along the nitrogen gradient, bulb growth followed a non-linear response, peaking at intermediate supply and declining under oversupply, with a stronger high-N penalty in Hytech. Nitrogen oversupply increased nitrate and free amino acid pools and lowered elemental bulb C:N ratios, while total phenolic content and quercetin glycoside levels declined. In contrast, relative levels of putatively annotated ACSO-like compounds increased as pyruvate-based pungency decreased, consistent with a compositional decoupling between sulfur-containing compound profiles and the pyruvate-based pungency signal under high N. Together, the results identify variety-specific thresholds and coordinated trade-offs linking nitrogen status to growth and the major quality-related metabolic domains in onion bulbs.\n                  <\/jats:p>","DOI":"10.3389\/fpls.2026.1886540","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T05:31:45Z","timestamp":1786685505000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Nitrogen supply modulates carbon\u2013nitrogen balance and metabolic profiles in contrasting onion varieties"],"prefix":"10.3389","volume":"17","author":[{"given":"M. L.","family":"Romo-P\u00e9rez","sequence":"first","affiliation":[{"name":"Quality of Plant Products 340e, Institute of Crop Science, University of Hohenheim","place":["Stuttgart, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C. H.","family":"Weinert","sequence":"additional","affiliation":[{"name":"Institute for Foods of Plant Origin, Max Rubner-Institut","place":["Karlsruhe, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B.","family":"Egert","sequence":"additional","affiliation":[{"name":"Institute for Foods of Plant Origin, Max Rubner-Institut","place":["Karlsruhe, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S. 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