Study On Morphological Model And Virtual Growth In Rice

Virtual crop is to simulate crop growth visually on computer by combining simulationtechniques of crop architecture and image processes, and could help readers to betterunderstand crop growth pattern, analyze the relationship between architecture and functionand explore plant ideotype and cultural regulation. On the basis of system analysis andexperimentation, this study aimed at developing morphogical models on organ, individualand canopy of rices and further realizing virtual growth of rice plant, by coupling outputs ofrice growth model and L-system. The expected results will lay foundation for constructingdigital and visual rice growth system.Based on the experiment observations, the shape of leaf blade, the change of leafangle and the relationships between the tiller leaf blade length and its synchronouslyemerging leaf blade length on main stem and between leaf blade length and its width werequantified, resepctively. The results showed that the normalized leaf blade shape could beexpressed in two quadratic equations, and the leaf angle changed in four stages withdevelopment of leaf age, the ratio of tiller leaf blade length to its synchronously emergingleaf blade length on main stem changed with tiller leaf number in quadratic equation, andthe relationship between leaf blade length and its width could be expressed in powerfunction. Then, coupled with simulation models of leaf age, leaf area and tiller number ofrice, a general model for predicting geometrical parameters of rice leaf blade wasdeveloped.After force analysis on a rice leaf, the gravity fraction in leaf normal direction keepsequilibrium with elasticity, a dynamic leaf curvature equation was deduced with someassumptions and solved with parameterization. Model validation with independentexperiment data indicated that the model could simulate the geometrical characteristics ofrice leaf blade under different growth conditions. The sensitivity analysis showed that theequation could well reflect the integrated effects of leaf length, leaf width, specific leafweight and leaf deformation coefficient, consistent with rice plant architecture. Simulation analyses, conducted on the equation with the experiment data, indicated that the leafcurvature equation could reasonably and reliably describe the change pattern of leaf shapecharacteristics of rice under different conditions.Stem and sheath are important organs for maintaining physiological process of crop,and their architecture is essential part of crop visualization. On the basis of the fieldexperiment, the change characteristics of internode length and width with elongationinternode number and the relationship between the length of leaf sheath and itssynchronously emerging organ on main stem were analyzed. Then, combined with outputsof growth model, such as leaf age and height of plant, a morphogical model on leaf sheathand internode was developed. Then, the model was validated with an independentexperiment data. The results showed that the model could be used to simulated the length ofsheath and internode with the RMSEs of 0.39cm and 0.20cm between the simulated andobserved values on lengths of leaf blade and internode, respectively.Based on field experiments with different cultivars and nitrogen application, thequantitative characteristics of panicle architecture were analyzed. The results showed thatthe ratio of length of primary branch to that of panicle could be characterized by a quadraticequation in terms of nodal number of branch on panicle axis. The number of secondarybranch changed linearly with the length of primary branch. Primary branch lied uniformlyon panicle axis and nodal distance of primary and secondary branch also had no significantchange. In addition, the output of growth model, such as grain number per panicle and thenumber of primary branch, was utilized to analyze the spatial distribution of secondarybranch. Finally, the architecture of rice panicle was simulated visually on computer.Based on literatures, the characteristics of rice root growth, such as root elongationtime, root number, elongation velocity and spreading direction, and influencing factorswere analyzed and summarized. The quantitative methods for modeling growth processesand architecture of rice roots were proposed. Furthermore, a preliminary virtual growth ofrice root was realized.Then, on the basis of biological patterns and field experiments, combined with theoutput of rice growth model, general organ elongation model and structural model for ricewere developed. Growth unit, containing internode and its adjacent leaf or ear, was used todescribe topological structure of rice plant. With logistic curve for simulating organelongation and according to the relationship of organ elongation and leaf age, a dynamicalstructural model of rice plant was developed from daily output of growth model. Model validation with the field experiment data showed that the model could well simulate plantarchitecture and organ elongation of rice under different varieties and environments.Finally, L-system was introduced and exampled on plant architecture modeling withrice. Combining architecture characteristic, virtual rice was realized visually on organ andindividual levels. To display crop canopy with discrepant organs and individual plants,differences between individuals in leaf age, tiller number and geometrical parameters oforgan in same position were quantified, and the random methodology was proposed togenerate rice canopy. Finally, the virtual growth of rice canopy on daily progress wasrealized.