title: NEMA, a functional-structural model of nitrogen economy within wheat culms after flowering. II. Evaluation and sensitivity analysis.
abstract: OBJECTIVE
  Simulating nitrogen economy in crop plants requires formalizing the interactions between soil nitrogen availability, root nitrogen acquisition, distribution between vegetative organs and remobilization towards grains. This study evaluates and analyses the functional-structural and mechanistic model of nitrogen economy, NEMA (Nitrogen Economy Model within plant Architecture), developed for winter wheat (Triticum aestivum) after flowering.
  
  
  METHODS
  NEMA was calibrated for field plants under three nitrogen fertilization treatments at flowering. Model behaviour was investigated and sensitivity to parameter values was analysed.
  
  
  RESULTS
  Nitrogen content of all photosynthetic organs and in particular nitrogen vertical distribution along the stem and remobilization patterns in response to fertilization were simulated accurately by the model, from Rubisco turnover modulated by light intercepted by the organ and a mobile nitrogen pool. This pool proved to be a reliable indicator of plant nitrogen status, allowing efficient regulation of nitrogen acquisition by roots, remobilization from vegetative organs and accumulation in grains in response to nitrogen treatments. In our simulations, root capacity to import carbon, rather than carbon availability, limited nitrogen acquisition and ultimately nitrogen accumulation in grains, while Rubisco turnover intensity mostly affected dry matter accumulation in grains.
  
  
  CONCLUSIONS
  NEMA enabled interpretation of several key patterns usually observed in field conditions and the identification of plausible processes limiting for grain yield, protein content and root nitrogen acquisition that could be targets for plant breeding; however, further understanding requires more mechanistic formalization of carbon metabolism. Its strong physiological basis and its realistic behaviour support its use to gain insights into nitrogen economy after flowering.
authors.affiliation: INRA, UMR 0462 Sciences Agronomiques Appliquées à l'Horticulture, F-49071 Beaucouzé Cedex, France. jessica.bertheloot@angers.inra.fr
authors.forename: Jessica
authors.initials: J
authors.lastname: Bertheloot
authors.forename: Qiongli
authors.initials: Q
authors.lastname: Wu
authors.forename: Paul-Henry
authors.initials: PH
authors.lastname: Cournède
authors.forename: Bruno
authors.initials: B
authors.lastname: Andrieu
mesh_terms: D000222:Adaptation, Physiological; D002244:Carbon / Q000378:metabolism; D003198:Computer Simulation; D003890:Desiccation; D005308:Fertilizers; D035264:Flowers / Q000502:physiology; D008027:Light; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D013997:Time Factors; D014908:Triticum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology
chemical_list: D005308:Fertilizers; D012987:Soil; D002244:Carbon; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen