Section: Scientific Foundations
Digiplante at INRIA
Derived from the AMAP model developed in the 1990s at CIRAD [54] , GreenLab's new formulation was introduced at LIAMA (Beijing) in 2000, through the GreenLab Associate Team with INRIA. Today, the model is studied and improved owing to the DigiPlant research team that is a joint team of researchers from INRIA, CIRAD and Ecole Centrale Paris. Some very close partnerships exist with LIAMA, China Agriculture University, Wageningen University, INRA, SupAgroMontpellier and AgroParisTech. The development of the GreenLab model is shared between all these partners, with strong interactions (International exchanges, common publications and joint PhD).
Our approach to develop the mathematical model of plant growth strongly relies on the plant organization described by botanists. This leads to relevant choices [6] in order to obtain an efficient method of factorization based on plant instantiations [2] . Plant development concerns organogenesis, i.e. the appearance of organs. Growth depends on photosynthesis that insures organ expansion. On the common assumption of the existence of a global pool of reserves, it is not necessary to consider local conditions and we can distinguish 3 steps to control plant development and growth.
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Computing organogenesis. It provides the number of organs produced by the buds. It may be determined by plant functioning and the level of trophic competition [20] .
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Computing biomass production and allocation. Leaf surface area is used to determine photosynthesis and the neat biomass production is shared between the different organs (whose numbers are known by the organogenesis step) according to their sinks to insure their expansion. The yield is thus computed according to the sizes and the weights of the different organs produced.
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Building plant architecture for visualization or to study interactions with the environment. This last step involves geometry applied to the results of the two previous steps.
For most applications in agronomy, only the first two steps are necessary, and no geometry is required.
