3D architectural modelling of aerial photomorphogenesis in white clover (Trifolium repens L.) using L-systems

The objective of this work was to construct a model of aerial development of clover that takes into account morphogenetic responses to the light environment, and to use it to analyse and understand these processes in terms of signal perception and integration. The plant model was interfaced with a Monte Carlo model that determines photosynthetically active radiation (PAR) and red/far-red ratio (R/FR) throughout the canopy, taking into account the absorption, reflection and transmission of light by individual leaves. Light intensity and quality were sensed by the plant model at discrete time intervals and at discrete sites of perception: apices, emerging internodes and petiole tips. This input regulated the final size of internodes and leaves, the vertical positioning of leaves, and the branching delay. The empirical relations (regression functions) quantifying this regulation were derived from data reported in the literature and original measurements. Simulations produced realistic Visualizations and quantitative characterizations of the modelled plants for different light treatments. These results were in general agreement with observations of real plants growing under similar conditions, suggesting that the dependence of organ size and position on light treatments can be regarded as an integration of the responses of individual plant organs to their local light environment. The model is used to describe the regulation of branch appearance and the impact, of self-shading on plant morphogenesis as a function of local light environment. (C) 2000 Annals of Botany Company.