Abstract: 【Objective】 Describing the morphology structure and growth process of plants in a digital way is an effective means of correctly understanding and expressing the development regulation of plants. In order to accurately describe and quantitatively analyze the grape trees with complex morphological structure, the digital expression and processing technologies of grape trees were studied in depth. 【Method】 The basic structure unit was divided and defined according to the morphological structure and growth process of grape tree, including the truck, perennial canes, new shoot and organs on the shoots. The new shoots include bearing and vegetative shoots. Organs on the shoots include buds, inflorescence, ears, secondary shoots, leaves and tendrils. Referencing the experience, habits, and trend of structure naming strategy at home and abroad, combining the actual field observation and following the temporal and space order of growth sequences of each structure unit, a naming scheme for the above ground structure units of grape trees at an annual rate was proposed. The first letters indicate the type and the figures showing the birth order of structure unit. The naming scheme also contains information of the growth and branching source relationship between the relative structure units. It integrated the shoot change process from the initial new shoot to the cane and then to the perennial cane under the perennial mechanism. The new shoots were constituted using an ordered set way in the scheme. On the basis of the naming scheme, the representation method of compound organs and complex operations was given, including representation method of complex organs such as bearing basal shoots and bearing shoot group; digital description of grape tree structure changes by artificial pruning; growth representation of grape trees at an annual rate; growth process backtracking of perennial grape trees; quantitative statistical analysis method of each structure unit. 【Result】 Taking the short shoot pruned V font shape Cabernet Sauvignon grape tree in Zhengzhou National Grape Germplasm Resources Garden and T font shape Xiangfei grape tree in the experimental greenhouse in Institute of Forestry and Pomology of Beijing Academy of Agricultural and Forestry Sciences as an example, the digital expression of the selected two trees was given respectively. The digital expression realized a clear representation of the two trees with complex structures, including the unique naming of each organ and the connection relationship of each other. On the basis of the structure expression, structure units on a new shoot were counted to make a quantitative statistic. The morphological structure change expression such as secondary shoot and tendril pruning and tree annual growth were illustrated as well. The application of digitized grape trees showed the universality and effectiveness of the method for the description of different forms and different growth periods of grape trees. 【Conclusion】 This study contributes to a more intuitive understanding of grape tree morphological structure and growth mode. It has important significance for constructing the functional-structural model, for realizing precisely describing morphological structure of grape trees, visualization expression and quantitative analysis, etc. The study also has important significance for quantitative calculating and simulating the condition, development and evolution of the internal factors of grape trees, and for further prediction and evaluation of these factors. At last, the structure unit definition and naming scheme have reference values to research the woody plants of similar morphological structures.

Key words: grape tree, morphological structure, growth and development, digitization, structure unit