Studies On Creation And Visualization Of Dynamic Simulation Model On Root Growth And Development In Tobacco (Nicotiana Tabacum L.)

Following the thoughts of crop-models domestically and internationally, using the systematic analysis and computer simulation technology, a object oriented three-dimensional model simulating the formation of root system architecture of tobacco was designed in this research, based on the data both from the field experiments conducted by the author during 2002-2003 and several field surveys. The model is comprised of three submodels, which is root growth and development submodel, root water-uptake submodel, shoot and root dry mass allocation submodel.It is assumed that root axis is consisted of a great deal of straight root segment that develop during one time step when the apex of former segment move to new position. These root segments have different growth direction. When the main root axis appeared, new branch axis may arise and every segment existed may growth and branch in each time step.The growth of root segment is determined by root elongation rate and growth direction, and the branch of root segment is determined by branch orientation, branch age, branch density and branch space etc. Based on the numerical relation between the parameters described above and environmental resources, the root growth and development model is created. This model is a daily-time step, dynamic model of tobacco root growth and spatial distribution. And at the same time, based on the numerical relation between soil water content, root water uptake rate, soil type, root number etc, root water-uptake model is established. This model is a daily-time step, dynamic model of tobacco root water uptake rate and soil water content. Based on the numerical relation between tobacco potential transpiration rate, root water uptake rate, tobacco water use efficient, root/shoot allocation ration of new assimilate etc. in different soil strength, shoot and root dry mass allocation model is established. It is also a daily-time step model.The model can not only simulation tobacco root growth and development, but also realize the coupling between root geometrical morphology and root function, realize the coupling between root simulation and shoot simulation.Finally, we use computer simulation technique OpenGL to carry out visualization. From the output 3-D pictures, we can see that the model can simulate fairly tobacco root growth and development in 3-D space.Applied the international common-used method for testing model, we verified the model. The results indicated that the simulative parameters, such as root length, root number, dry weight etc., show fairly the rhythm of tobacco root growth and development. And the simulative results are closed to the observed data, and have bigger correlation with it. All of these show that applied the model simulate tobacco root growth and development is effective.In this paper, the link of agricultural knowledge and computer technology was realized. This model system not only has advantages in systematicness, mechanism and visualization, but also has distinct biological significance and highly accuracy. Moreover, because the linker of input and output was designed in this model, it can be linked easily to other model system. The model can not only being a tool to study tobacco root, but also can provide thought for other plant root model research. The model can also link with tobacco shoot model, which make the study of crop model integrated.