MODELLING PLANT GROWTH AND ARCHITECTURE : SOME RECENT ADVANCES AND APPLICATIONS TO AGRONOMY AND FORESTRY

Modelling plant structure and growth has undergone major changes in the last decades along two major lines: the integration of ecophysiological knowledge in process-based models which often lack a description of plant topology and geometry, and the generation of 3-D virtual plants using morphogenetic models which simulate the architectural development in a stable and homogeneous environment. There is now a trend to merge these two approaches, that is to link plant architecture and functioning. This trend is based on the recognition that plant structure: is the joint output of the physiological processes (water and carbon balance, etc.) and the morphogenetic programme of the plant; determines the external environment of the trees which itself regulates their functioning (competition for space, light attenuation, etc.); and directly conditions the physiological processes within the tree (hydraulic structure, selfshading, allocation of photosynthates, etc.). Such models can be used in agronomy and forestry in various ways: to investigate the effects, local and global, immediate and delayed, of the biophysical environment on plant morphogenesis and yield; to study light attenuation through the canopy, to analyse the transport of water and the allocation of photosynthates within the plant; to analyse the competitive interactions among different plants in the same stand; to calibrate remote sensing techniques and to visualize large landscapes. (Resume d'auteur)