Abstract: Based on the analysis of the rule of tobacco root growth and development, a tobacco root model was built by crop simulation techniques, which could be used to describe quantitatively the dynamic relationships between root growth and development of tobacco and environments. Then parameters of the models were determined using the measured data taken from the "root box" experiments held at the Henan Agricultural University. After running the root models, parameters, such as the root number, root length, index of root length and density of root length etc. could be obtained, which would provide a new tool in future studies revolving crop roots. Finally, the tobacco root models were tested using the experimental data in 2003，and the results show that there are significant relationships between the simulated and measured data with correlation coefficients between 0.9540-0.9896 for root number, root length of the first and second order, root length density and root length index etc. The results mentioned above indicate that the model behaves well to predict tobacco root morphological development.

Key words: Tobacco (Nicotiana tabacum Linn.), Root, Simulation model, Morphological development