Nitrogen Source Release Dynamics Drive the Carbon-Nutrient Coupling Mechanism in the Fast-Growing Tree Ochroma lagopus: Organ-Specific NSCs Allocation and Coordinated Adaptation of N-P-K Stoichiometry

Nitrogen Source Release Dynamics Drive the Carbon-Nutrient Coupling Mechanism in the Fast-Growing Tree Ochroma lagopus: Organ-Specific NSCs Allocation and Coordinated Adaptation of N-P-K Stoichiometry | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Nitrogen Source Release Dynamics Drive the Carbon-Nutrient Coupling Mechanism in the Fast-Growing Tree Ochroma lagopus: Organ-Specific NSCs Allocation and Coordinated Adaptation of N-P-K Stoichiometry Juncheng Han, Wenhao Zhang, Jialan Chen, Weisong Zhu, Gang Chen, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9195890/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study investigated two-year-old seedlings of the fast-growing tree species Ochroma lagopus under a control (CK) and treatments with urea (N1–N3) and slow-release fertilizer (H1–H3) at rates of 300, 450, and 600 g per tree. We systematically revealed the organ-level “carbon‑nutrient coupling” strategies and physiological mechanisms driven by nitrogen‑source release dynamics. Nitrogen addition consistently increased non‑structural carbohydrate (NSCs) accumulation; leaf NSCs rose by 19.53% (N3) and 23.48% (H3) under high nitrogen. However, nitrogen‑source patterns dictated NSC allocation: urea favored starch (leaf starch increased by 81.90% in N2), forming a “high‑nutrient‑starch” growth‑oriented strategy, whereas slow‑release fertilizer increased soluble sugars (sugar/starch ratio rose 24.35% in H2), leading to a “homeostasis‑sugar” stress‑resistance strategy. Urea triggered rapid root N and P accumulation (root N up 70.60%) and K redistribution to leaves (leaf K up 44.39%), while slow‑release fertilizer maintained N homeostasis, preferentially supplying leaves and roots and reducing branch N. Stoichiometric ratios were the core regulators of carbon allocation, showing plasticity in the order root > branch > leaf, with root K/P being most plastic. Roots were the most responsive organ, and the soluble‑sugar/starch ratio acted as a key physiological hub. A growth model was constructed in which nitrogen dynamics set the strategy, organ functional differentiation shapes responses, stoichiometric balance serves as the central regulatory axis, and carbon and nutrients interact bidirectionally as “nutrients activate carbon fixation and carbon supply reciprocates nutrient metabolism.” For fast‑growing plantations, urea is recommended for rapid biomass accumulation and slow‑release fertilizer for enhanced stress resistance, providing theoretical support for carbon‑sink forest cultivation and sustainable management. Ochroma lagopus Nitrogen addition Non-structural carbohydrates (NSCs) Nutrient stoichiometry Carbon–nutrient coupling Organ-specific response Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9195890","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":619179308,"identity":"3beb5971-0c41-4c69-ab68-b23e1e12e684","order_by":0,"name":"Juncheng Han","email":"","orcid":"","institution":"Southwest Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Juncheng","middleName":"","lastName":"Han","suffix":""},{"id":619179309,"identity":"a20ae65b-59f8-4423-a121-a8f4018a359f","order_by":1,"name":"Wenhao Zhang","email":"","orcid":"","institution":"Southwest Forestry 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Carbon–nutrient coupling, Organ-specific response","lastPublishedDoi":"10.21203/rs.3.rs-9195890/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9195890/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigated two-year-old seedlings of the fast-growing tree species \u003cem\u003eOchroma lagopus\u003c/em\u003e under a control (CK) and treatments with urea (N1\u0026ndash;N3) and slow-release fertilizer (H1\u0026ndash;H3) at rates of 300, 450, and 600 g per tree. We systematically revealed the organ-level \u0026ldquo;carbon‑nutrient coupling\u0026rdquo; strategies and physiological mechanisms driven by nitrogen‑source release dynamics. Nitrogen addition consistently increased non‑structural carbohydrate (NSCs) accumulation; leaf NSCs rose by 19.53% (N3) and 23.48% (H3) under high nitrogen. However, nitrogen‑source patterns dictated NSC allocation: urea favored starch (leaf starch increased by 81.90% in N2), forming a \u0026ldquo;high‑nutrient‑starch\u0026rdquo; growth‑oriented strategy, whereas slow‑release fertilizer increased soluble sugars (sugar/starch ratio rose 24.35% in H2), leading to a \u0026ldquo;homeostasis‑sugar\u0026rdquo; stress‑resistance strategy. Urea triggered rapid root N and P accumulation (root N up 70.60%) and K redistribution to leaves (leaf K up 44.39%), while slow‑release fertilizer maintained N homeostasis, preferentially supplying leaves and roots and reducing branch N. Stoichiometric ratios were the core regulators of carbon allocation, showing plasticity in the order root\u0026thinsp;\u0026gt;\u0026thinsp;branch\u0026thinsp;\u0026gt;\u0026thinsp;leaf, with root K/P being most plastic. Roots were the most responsive organ, and the soluble‑sugar/starch ratio acted as a key physiological hub. A growth model was constructed in which nitrogen dynamics set the strategy, organ functional differentiation shapes responses, stoichiometric balance serves as the central regulatory axis, and carbon and nutrients interact bidirectionally as \u0026ldquo;nutrients activate carbon fixation and carbon supply reciprocates nutrient metabolism.\u0026rdquo; For fast‑growing plantations, urea is recommended for rapid biomass accumulation and slow‑release fertilizer for enhanced stress resistance, providing theoretical support for carbon‑sink forest cultivation and sustainable management.\u003c/p\u003e","manuscriptTitle":"Nitrogen Source Release Dynamics Drive the Carbon-Nutrient Coupling Mechanism in the Fast-Growing Tree Ochroma lagopus: Organ-Specific NSCs Allocation and Coordinated Adaptation of N-P-K Stoichiometry","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-08 16:38:45","doi":"10.21203/rs.3.rs-9195890/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e3fb7822-7f64-419a-a377-7cca5939cdbb","owner":[],"postedDate":"April 8th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-21T04:24:45+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-08 16:38:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9195890","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9195890","identity":"rs-9195890","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}