Abstract: 【Objective】 Modeling dynamics of each organ size in cotton growth process, then a virtual growth system for cotton was implemented to provide a technical basis for research of virtual farming. 【Method】 Based on the potted plant research of cotton variety, sowing date, nitrogen, water and DPC in a summer seasons of 2005 and 2006, with the systematic analysis principle and mathematical modeling technique applied to cotton morphogenesis, a morphological model , which includes several sub-models of leaf, stem, boll, and so on, was developed by the quantitative analyses of experimental data. And a virtual growth system for cotton was implemented with usage of OpenGL for 3D graphic and MFC for graphical user interface. 【Result】 The results showed that the dynamic change of each organ size could be characterized by logistic equation in relation to GDD, nitrogen, water and DPC. The model was validated by the data from 2006, and the mean RMSEs were 0.85, 0.82, 0.87, 0.57, 0.086, 0.65, 0.74, 0.8, 0.73, 0. 016, 0.36 and 0.4 cm for main stem leaf length and width, main stem leaf stalk length, main stem internode length and diameter, fruiting branch leaf length and width, fruiting branch leaf stalk length, fruiting node length and diameter, and boll length and width, respectively. Then NURBS was applied to simulate the shape of cotton leaf and boll, internode and petiole were treated as cylinder. Finally, a cotton growth system which comprises of models, database and interface was implemented with OpenGL on the platform of Microsoft Visual C++ 6.0. 【Conclusion】 The system can be used to simulate the real growth process of each organ, individual and group with some inputs.

Key words: cotton, GDD (growing degree days), morphogenesis model, visualization, system