Modéliser la compétition entre cultures et adventices pour l'eau pour la conception de stratégies de gestion des adventices agroécologiques et résilientes au changement climatique.

The FLORSYS model simulates the multi-annual weed dynamics in arable crops from cropping system and pedoclimate. It is used as a virtual field to evaluate cropping systems in terms of weed impacts on crop production and biodiversity. Its current version includes plant–plant competition for light and nitrogen, but not yet for water, which limits its use in the context of climate change, where lack of water is assumed to become more frequent. This article presents the construction of a plant–plant water competition submodel for FLORSYS, anchored on its pre-existing variables. In the submodel, plant water uptake is a function of soil water availability, plant water demand and the water demand of neighbouring plants. In the case of insufficient uptake, the submodel represents the impact of water stress on plant morphology and photosynthesis, in conjunction with nitrogen and shade stress. Once evaluated, the new FLORSYS version will be used to identify rules for guiding the co-design of sustainable and resilient systems to climate change.