Multiscale topological and geometrical representation of plant architecture
Résumé
In the last decade, a mathematical formalism has been introduced to represent the complexity of plant branching structures at different scales. Using Multiscale Tree Graph (MTG), it was possible to capture the topology and the geometry of a multitude of plant species at different scales in a precise manner. However, the use of this formalism was initially restricted to quantitative acquisition and analysis of plant branching systems. Its use in mechanistic models of plant growth remained elusive. In this paper, we extend the MTG formalism to comply with the requirements of Functional-Structural Plant Models (FSPM) at different scales. This includes a continuous representation of plant properties at different scales, the possibility to grow MTG using developmental rules, and to encode the dynamic structure at different developmental stages as a time-serie. Interestingly, MTGs are compatible with L-systems, a formalism commonly used to model FSPMs, and offer in this context the possibility to manipulate multiscale branching structures. In addition, generic graph-based algorithms have been designed to model flows through plant structure at different scales and interaction with environment. Illustrations of the flexibility of our approach are presented in the context of FSPMs. They cover the acquisition, modelling and visualisation of plant structures and their development. This multiscale formalism is used by many plant modeling groups and is available in OpenAlea as a central data-structure to couple heterogeneous models. More generally, this formalism paves the way of more generic models of representation of plant architecture that can be used to share large plant databases obtained from plant phenotyping and simulations.