Root system architecture:: from its representation to the study of its elaboration

Modelling the architecture of the root system is a recent approach, since almost all such models have appeared during the last 10 years. In a short review of these architectural models, we define several steps in their evolution, which also correspond to different goals. The main basic idea was to translate and to combine morphogenetic rules, described at the root level, in order to produce a quantitative representation of the global object: the root system. The inclusion of stochastic processes appeared to be an economic way to simulate realistic root systems, staying at this organisation level, because of the unpredictable characteristics of some developmental processes, which lead to large variations from one root system to another. In several applications, these models were shown to be helpful for integrating knowledge at the root level regarding soil-root interactions. In the most recent works, a more integrated approach is proposed, in which the components of the root system appear according to a morphogenetic programme, and interact by contributing and responding to the endogenous context of resource availability. ((C) Inra/Elsevier, Paris.).