Virtual chrysanthemum

An integration of structural and physiological models is used to simulate three-dimensional (3D) plant growth and visual appearance of cut chrysanthemum, reacting on environmental factors.

Measurements to calibrate the model include geometrical data of digitised plants as well as a number of measurements and observations on harvested plants, including biomass per organ. The structural module consists of an L-system, i.e. a set of rules describing morphological development. This L-system calculates temperature and light driven development, branching pattern, and flower formation. In this structural model existing rules for physiological processes are incorporated, enabling calculation of carbon dynamics. The radiosity method is used to calculate light absorption of every organ (leaf) at an hourly basis. Hourly photosynthesis per leaf is calculated according to the biochemical model of Farquhar taking into account absorbed light, CO2, and temperature at hourly intervals. A relative sink strength approach is used to distribute the available assimilates among organs at a daily basis.

Since the 3D crop consists of a set of individual plants, simulation of plant to plant competition for light is enabled. The modelling of temperature and light level effects on growth and flower quality is based on trial data at different temperature and plant density levels. The model is able to visualise different flower qualities in terms of flower number and branching patterns per plant. The results show the integrative effects of local sinks, specific in time and 3D position, on structure and ornamental quality at plant level.