Modelling plant growth and architecture: Some recent advances and applications to agronomy and forestry

Modelling plant structure an 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: (i) is the joint output of the physiological processes (water and carbon balance, etc.) and the morphogenetic programme of the plant, (ii) determines the external environment of the trees which itself regulates their functioning (competition for space, light attenuation, etc.), and (iii) directly conditions the physiological processes within the tree (hydraulic structure, self-shading, 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.