Résumé
Species mixtures are of great interest to promote low-input agricultural practices whilemaintaining agricultural production. For example, winter oilseed rape sown with a frostsensitive legume reduces the use of nitrogen fertilizer and herbicide while maintaining yield atlevels equivalent to pure cropping (Lorin et al., 2016). A disadvantage of such mixtures is thatthe legume might compete with the cash crop for resources and reduce yield. To optimizemanagement of these mixtures, it is necessary to better understand the ecophysiologicalprocesses that drive the sharing of resources between plants (e.g. carbon and nitrogen).Mechanistic functional-structural modeling (FSM) is particularly suitable for such studies as itallows the analysis of the processes underlying plant-plant interactions and integrates boththe architectural growth processes of the plant and its functioning (e.g. acquisition/allocationof resources) (Louarn and Song, 2020). For example, the model Virtual Grassland (Louarn etal., 2014) simulates competition for C, N and water between several herbaceous and legumespecies. However, no FSM for mixtures of annual crops with frost sensitive legume thatconsiders the feedback of the carbon/nitrogen functioning in both shoots and roots has beendeveloped so far. Such a modeling approach is shown in this study, with the aim of fillingknowledge gaps on the role of carbon-nitrogen interactions in plastic responses of plants inmixtures, by taking the case study of winter oilseed rape sown with frost sensitive fababeanat vegetative stage.