Development of the virtual paddy field system for researching a light-interception efficiency of a rice plant

We developed a paddy field model “the virtual paddy field system” for researching a highyielding cultivation method and a strategy of rice breeding. The electromagnetic 3-D digitizer was used to obtain the structure of a rice plant. The three dimensional coordinates of nine points on the edge of each leaf were measured with this equipment and the spatial arrangement of leaves of one plant was assembled. Using the detailed solid structure of a single plant, the three dimensional model of paddy field that consists of some rice plants was constructed and the program for evaluating a light-interception efficiency of paddy field was made. This system calculates the area of leaves receiving direct sunlight and the percentage of irradiated leaf area to total leaf area of single plant inside a paddy field at any angle of elevation and any azimuth angle of the sun. It can also evaluate the light-interception efficiency of virtual paddy field that consists of rice plants of which leaf length, leaf angle, internode length or leaf shape, was changed. And it can also be applied to the virtual paddy field with any planting distance. By repeating these simulation experiments, we will be able to recognize the ideal plant structure and the adequate cultivation method for high-yielding. Our virtual paddy field system is useful for high-yielding rice cultivation and rice breeding.