A coupled architecture and physiology 3D growth model for young longan tree

A longan (Dimocarpus longan Lour.) growth and development simulation model was created by integrating existing knowledge of different aspect of the Longan architecture and physiology. Field investigation and measurements were conducted in longan orchard in order to acquire architectural characteristics of longan tree. The three-dimensional canopy model of longan is consisted of trunk, branches and leaves. The basic unit of stem is a parameterized segment. The 3D segment was described with cone. The leaves were depicted using parametric NURBS surface. The 3D canopy was presented by connecting the elements according to the tree architecture and topology. Hourly photosynthesis per leaf under various environmental conditions was calculated, and the total photosynthesis assimilation of the young longan in growing season was estimated. Based on source-sink partitioning theory, the biomass was allocated among organs according to the organ expansion rate and age. Tree growth is driven by the available photosynthetic products after respiration losses. The development of longan was reshaped by expanding of existing organs or generating new organs corresponding to the increments of assimilation. Thus, the simulation of the dynamic growth processes of young longan under certain environmental factors was realized. A Tree growth simulation prototype system was implemented. It includes modeling of tree morphological structure, accumulating and partitioning assimilation products among different organs, and visualizing the partitioning outcome. The simulation of fruit tree growth in virtual plant environment will be useful to understand the longan growth and to develop strategies to improve fruits production.