title: Characterization of the interactions between architecture and source-sink relationships in winter oilseed rape (Brassica napus) using the GreenLab model.
abstract: OBJECTIVE
  This study aimed to characterize the interaction between architecture and source-sink relationships in winter oilseed rape (WOSR): do the costs of ramification compromise the source-sink ratio during seed filling? The GreenLab model is a good candidate to address this question because it has been already used to describe interactions between source-sink relationships and architecture for other species. However, its adaptation to WOSR is a challenge because of the complexity of its developmental scheme, especially during the reproductive phase.
  
  
  METHODS
  Equations were added in GreenLab to compute expansion delays for ramification, flowering of each axis and photosynthesis of pods including the energetic cost of oil synthesis. Experimental field data were used to estimate morphological parameters while source-sink parameters of the model were estimated by adjustment of model outputs to the data. Ecophysiological outputs were used to assess the sources/sink relationships during the whole growth cycle.
  
  
  RESULTS
  First results indicated that, at the plant scale, the model correctly simulates the dynamics of organ growth. However, at the organ scale, errors were observed that could be explained either by secondary growth that was not incorporated or by uncertainties in morphological parameters (durations of expansion and life). Ecophysiological outputs highlighted the dramatic negative impact of ramification on the source-sink ratio, as well as the decrease in this ratio during seed filling despite pod envelope photosynthesis that allowed significant biomass production to be maintained.
  
  
  CONCLUSIONS
  This work is a promising first step in the construction of a structure-function model for a plant as complex as WOSR. Once tested for other environments and/or genotypes, the model can be used for studies on WOSR architectural plasticity.
authors.affiliation: AgroParisTech, UMR Environnement et Grandes Cultures, Thiverval-Grignon, France. alexandra.jullien@agroparistech.fr
authors.forename: Alexandra
authors.initials: A
authors.lastname: Jullien
authors.forename: Amélie
authors.initials: A
authors.lastname: Mathieu
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Allirand
authors.forename: Amélie
authors.initials: A
authors.lastname: Pinet
authors.forename: Philippe
authors.initials: P
authors.lastname: de Reffye
authors.forename: Paul-Henry
authors.initials: PH
authors.lastname: Cournède
authors.forename: Bertrand
authors.initials: B
authors.lastname: Ney
mesh_terms: D000465:Algorithms; D029688:Brassica napus / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D005638:Fruit / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D008954:Models, Biological; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism