The amount of absorbed radiation has a large influence on development, expansion and architecture of plants. We propose a structural-functional approach to analyse and model the phenotypic variability of plant architecture in response to light intensity in Arabidopsis thaliana. 3D virtual plants were built for eight genotypes and various light treatments between 2.5 and 17.5 mol m-2 d-1. Columbia and its mutant serrate are presented here as a sample of the studied genotypes. Radiative balance was calculated on these 3D representations, and allowed accurate estimations of the amount of absorbed radiation by the plants. Robust positive relationships related to the amount of absorbed radiation were obtained for (i) leaf initiation rate and (ii) relative leaf expansion rate. The duration of leaf expansion was negatively related to the amount of incident radiation. The model presented here allowed to deepen our knowledge of the phenotypic variability in response to light intensity for different genotypes and to model the genotype-environment interaction and the phenotypic variability.