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 o f clover that takes into account morphogenetic responses to the light envir onment, and to use it to analyse and understand these processes in terms of signal perception and integration. The plant model was interfaced with a M onte 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. Lig ht intensity and quality were sensed by the plant model at discrete time in tervals and at discrete sites of perception: apices, emerging internodes an d petiole tips. This input regulated the final size of internodes and leave s, the vertical positioning of leaves, and the branching delay. The empiric al relations (regression functions) quantifying this regulation were derive d from data reported in the literature and original measurements. Simulatio ns produced realistic Visualizations and quantitative characterizations of the modelled plants for different light treatments. These results were in g eneral agreement with observations of real plants growing under similar con ditions, suggesting that the dependence of organ size and position on light treatments can be regarded as an integration of the responses of individua l plant organs to their local light environment. The model is used to descr ibe the regulation of branch appearance and the impact, of self-shading on plant morphogenesis as a function of local light environment. (C) 2000 Anna ls of Botany Company.