The acquisition of inorganic forms of carbon and nitrogen, and their transformation into organic compounds are key components of plant growth. Large research efforts have been dedicated to investigate these processes and quite a detailed conceptual view of C and N economy of plants is available. By contrast, computer models simulating the whole plant or crop level are not based on mechanistic integration of these processes, but rather use some hypothetical «driving relations », originating e.g. from teleonomy, optimisation theory, functional equilibrium, etc.

We will review the main approaches used and motivate our work to build a more mechanistic frame to model C and N economy. C-N Wheat is intended to be tool to investigate traits of importance for productivity under limited resources and to conceive ideotypes.

A key feature was to consider the main forms of C and N compounds (e.g. structure, sugars, starch, nitrates, proteins, amino acids), and to express by differential equations the processes involved in their formation, degradation, and transfer within plant architecture.

At the moment the model simulates the post-flowering period, with an hourly time step. With parameters taken or estimated from the bibliography, the model was able to simulate realistically the distribution of C and N compounds in the whole plant and their changes at time scales from a few hours to the whole grain filling period. Current developments address the extension to the preflowering period.

Authors of C-N Wheat are Romain Barillot, Camille Chambon and Bruno Andrieu. The work is done as part of the BREEDWHEAT ANR project, in the framework of the Investments for the Future.