A nitrogen limitation causes important effects on the development and the growth of the plant that presents an adaptative response under such conditions. The plasticity of the root system is an essential element of this response. The objective of this study was to analyze the response of the root system to a nitrogen limitation by trying to take into account the whole plant functioning. We chose a modelling approach to simulate the whole plant functioning in Arabidopsis thaliana with a detailed description of the morphogenetic processes of the root system under contrasted nitrogen conditions. Experiments were carried out under cross conditions carbon and nitrogen nutritions to specify these effects on the root system architecture and to collect data for our modelling approach of the whole plant. Most of our study is on one genotype, the ecotype Wassilewskija (Ws-0), and proposes an analysis framework for future studies on genetic variability.