Managing Nitrogen Sources in Soybean–Rhizobium Symbiosis During Reproductive Phenological Stage: Partitioning Symbiotic and Supplemental N with 15N
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Le résumé fourni par la source
Understanding how supplemental nitrogen (N) interacts with biological N2 fixation (BNF) in modern soybean cultivars is essential for designing fertilization strategies that avoid unnecessary N inputs. We investigated N partitioning among soil, fertilizer and symbiotic sources in soybean grown in a greenhouse pot experiment on a tropical Oxisol. Plants were inoculated with Bradyrhizobium and subjected to four N managements: no external N, soil-applied 15N-urea (20 kg N ha−1), foliar 15N-urea (2 kg N ha−1, 0.7% w/v), and the combination of soil + foliar N. Using 15N isotope dilution, we quantified N derived from the atmosphere (NDFA), fertilizer (NDFF) and soil (NDFS) at organ and whole-plant scales, and related these fractions to nodulation, nitrogenase activity and yield. In the absence of external N, NDFA exceeded 97% in all organs, indicating a strong reliance on BNF and efficient internal N remobilization during grain filling, accompanied by higher leaf nitrate reductase activity. Soil and soil + foliar N markedly increased NDFF and NDFS while suppressing nodulation (particularly at V4) and reducing nitrogenase activity, yet they did not improve grain yield or vegetative biomass. Foliar N alone had only modest effects on N partitioning and did not enhance yield. Under these tropical soil conditions, symbiotic fixation and internal N remobilization were sufficient to meet grain N demand, highlighting the limited agronomic benefit and potential ecological cost of supplemental N during reproductive growth.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- Managing Nitrogen Sources in Soybean–Rhizobium Symbiosis During Reproductive Phenological Stage: Partitioning Symbiotic and Supplemental N with 15N
- Date Crossref
- 22/12/2025
- Éditeur
- MDPI AG
- Type
- journal-article
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Universidade de São Paulo pays non établi dans la noticeUniversité ou école supérieure
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Universidade Estadual Paulista (Unesp) pays non établi dans la noticeUniversité ou école supérieure
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University of São Paulo Center for Nuclear Energy in Agriculture pays non établi dans la noticeUniversité ou école supérieure
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Luiz de Queiroz College of Agriculture pays non établi dans la noticeUniversité ou école supérieure
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Paraguayan Institute of Agrarian Technology Department of Soils pays non établi dans la noticeStructure de recherche
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Faculty of Agricultural and Technological Sciences pays non établi dans la noticeUniversité ou école supérieure
Universidade de São Paulo, Universidade Estadual Paulista (Unesp) et Center for Nuclear Energy in Agriculture — University of São Paulo, avec 3 autres affiliations.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.