MAppleT: simulation of apple tree development using mixed stochastic and biomechanical models

International audienceConstruction of architectural databases over years is time consuming and cannot easily capture the event dynamics, especially when both tr ee topology and geometry are considered. The present project aimed to bring together models of topology and geometry in a single simulation such that the architecture of an apple t ree may emerge from process interactions. This integration was performed using L-systems. A m ixed approach was developed based on stochastic models to simulate plant topology and me chanistic model for the geometry. The succession of growth units (GUs) along axes and the ir branching structure were jointly modeled by a hierarchical hidden Markov model. A bi omechanical model, derived from previous studies, was used to calculate stem form a t the metamer scale, taking into account the intra-year dynamics of primary, secondary and f ruit growth. Outputs consist of 3D mock- ups geometric models representing the progression o f tree form over time. To asses these models, a sensitivity analysis was performed and de scriptors were compared between simulated and digitized trees, including the total number of GUs in the entire tree, descriptors of shoot geometry (basal diameter, length), and des criptors of axis geometry (inclination, curvature). In conclusion, in spite of some limitat ions MAppleT constitutes a useful tool for simulating development of apple trees in interactio n with gravity

MAppleT: simulation of apple tree development using mixed stochastic and biomechanical models

International audienceConstruction of architectural databases over years is time consuming and cannot easily capture the event dynamics, especially when both tr ee topology and geometry are considered. The present project aimed to bring together models of topology and geometry in a single simulation such that the architecture of an apple t ree may emerge from process interactions. This integration was performed using L-systems. A m ixed approach was developed based on stochastic models to simulate plant topology and me chanistic model for the geometry. The succession of growth units (GUs) along axes and the ir branching structure were jointly modeled by a hierarchical hidden Markov model. A bi omechanical model, derived from previous studies, was used to calculate stem form a t the metamer scale, taking into account the intra-year dynamics of primary, secondary and f ruit growth. Outputs consist of 3D mock- ups geometric models representing the progression o f tree form over time. To asses these models, a sensitivity analysis was performed and de scriptors were compared between simulated and digitized trees, including the total number of GUs in the entire tree, descriptors of shoot geometry (basal diameter, length), and des criptors of axis geometry (inclination, curvature). In conclusion, in spite of some limitat ions MAppleT constitutes a useful tool for simulating development of apple trees in interactio n with gravity

Using computational plant science tools to investigate morphological aspects of compensatory growth

Models of cotton plant architecture expressing several physiological hypotheses about plant resource use and responses to damage are incorporated in the traditional research cycle to investigate the phenomena of compensation for defoliation. Two separate approaches to modelling the uptake and allocation of carbon are used: a detailed bottom-up physiology model expressing ideas about local control, and a top-down, canonical approach where qualitative knowledge about plant responses to defoliation are modelled as flows between plant physiological compartments. The two models provide contrasting methods for developing explanations for the underlying pattern of responses observed in the plants