Modeling of biomasse acquisition and partitioning in the architecture of sunflower

A mathematical sunflower growth model is presented that simulates interactions between plant structure and function. Dual-scale automaton is used to simulate plant organogenesis from germination to maturity on the basis of organogenetic growth cycles that have constant thermal time. Plant fresh biomass production is computed from transpiration, assuming transpiration efficiency to be constant and atmospheric demand to be the driving force, under non-limiting water supply. The fresh biomass is then distributed among expanding organs according to their relative demand. Demand for organ growth is estimated from kinetics of potential growth rate for each organ type. These are obtained through parameter optimization against an empirical, morphological data sets by running the model in inverted mode. Potential growth rates are then used as estimates of sink strength in the model. These and other "hidden" plant parameters are calibrated using the nonlinear, least squares method. The resulting model accurately simulated the dynamics of plant growth, architecture and geometry, enabling 3D visualization. The potential of the model's underlying concepts to simulate the plant's morphological plasticity in different resource situations is discussed. (Resume d'auteur)