Studies On Simulation Model Of Morphologial Development In Rice Plant

Modeling morphological structure in rice is of significant importance for realizing virtual and digital growth of rice plant. Based on through time-course observations on morphological characteristics of above-ground organs in rice under different nitrogen rates and cultivar types, dynamic development processes of different organs with GDD as main line were simulated, and the effectiveness of nitrogen rates and water regimes on organ growth were quantified. The results indicated that the present model had a good performance in predicting organ morphological growth on rice plant, and thus laid a foundation for further constructing virtual rice plant.Based on time-course observations on leaf morphological properties (leaf length and leaf width) on main stems and tillers under different nitrogen rates and water regimes with four rice cultivars, the change patterns of leaf morphology with growth progress and environmental factors were characterized, and a dynamic model was developed to simulate time-course growth characters of different leaves on rice plant. The results showed that the growth dynamics of leaf length on stem and tiller could be described with a logistic model, the change pattern of final leaf length with different leaf positions on main stem exhibited two quadratic patterns, the final leaf length on tillers follows the ratio of the simultaneous leaf length on tiller to main stem, the maximum leaf width for different leaf positions on main stem and tillers could be quantified with a quadratic equation, the dynamic leaf width with leaf length direction at different GDD of a single leaf on main stem and tillers could be described with a quadratic curve, the general relationships between the final leaf length and maximum leaf width on main stem and tillers could be described with exponential (first leaf and flag leaf) and quadratic (other leaves) equations. The effects of nitrogen and water conditions on leaf growth were quantified by the effectiveness values of nitrogen concentration and water content in leaves. The model was validated with independent experiment data of different nitrogen rates, and the mean RMSEs of leaf length at varied GDD, final leaf length and leaf width were 0.75 cm, 0.96 cm and 0.71 cm on main stem, 0.82 cm, 0.88 cm and 0.79 cm on tillers, respectively. Based on time-course observations on leaf angle and curvature characteristics at different leaf positions of stem and tillers under different nitrogen rates and water conditions with four rice cultivars, a dynamic leaf angle equation was built and deduced curvature equation through force analysis on rice leaf and the equation was solved with parameterization. In addition, the effects of leaf angle change on leaf curvature under different nitrogen and water conditions were quantified with the nitrogen concentration and water content in leaf. Simulation analyses were conducted with the independent field experiment data and the results showed that the leaf curvature equation could reasonably and reliably describe the change pattern of leaf shape characteristics of rice under different conditions.Based on time-course observations on leaf color changes at different leaf positions of stem and tillers under different nitrogen rates and water conditions with four rice cultivars, we developed a simulation model on leaf color dynamic changes in rice in relation to GDD. Leaf color changes in the model were described with SPAD in three phases. The first phase during leaf growth period was based on the exponential relationship of leaf color to cumulative GDD; the second phase during leaf function period was represented with a relative stable SPAD; the third phase during leaf senescence period was described in a quadratic equation between SPAD and GDD. In addition, the effects of nitrogen and water conditions on leaf color were quantified through the effectiveness values of leaf nitrogen concentration and water content in relation to SPAD. Then, the RGB values were further predicted from the changing SPAD. The model was validated with the independent field experiment data involving different rice cultivars and nitrogen rates. The average RMSEs between the simulated and observed SPAD dynamics at different leaf positions were 2.58, 3.69, 3.82, respectively, for three leaf color phases on main stem, 4.65, 4.39, 3.51, 4.25, respectively, for four individual tillers in rice, and 2.98, 3.25, respectively, for SPAD and R, G values.Based on time-course observations and quantitative analysis of leaf sheath and internode at different leaf positions with the experiments of different varieties, water regimes and nitrogen rates, we built a dynamic simulation model on growth processes of leaf sheath and internode. The growth dynamics of leaf sheath and internode on stem and tiller could be described respectively with a logistic model, the change of tiller sheath length was described with quadratic equation on the relationship of synchronous leaf sheath the change of internode diameter was described with linear equation on the relationship of internode length and diameter. The effects of nitrogen and water conditions on leaf sheath and internode growth were quantified by the effectiveness values of nitrogen concentration and water content in leaf sheath and internode. The model was validated with the independent field experiment data involving different nitrogen rates. The mean RMSEs of leaf sheath on stem, primary tiller and were 0.65 cm, 0.52 cm and 0.46 cm, respectively, and internode length and diameter were 0.42 cm and 0.15 cm, respectively.Based on time-course observations on morphological properties of panicles (panicle length, length and number of, primary branches and secondary branches, spikelet number on branches, and nodal distances of primary and secondary branches) on main stems and tillers under different nitrogen rates and water regimes with four rice cultivars, the change patterns of panicle morphology with growth progress and environmental factors were characterized, and a dynamic model was developed to simulate dynamic growth characters and morphological formation of different panicles on rice plant. The growth dynamics of panicle length on stem and tiller could be described with a logistic model in relation to GDD, same pattern for the growth of primary branches and secondary branches. The ratio of primary branch to panicle and secondary branch to primary branch in final length could be characterized by a quadratic equation in terms of nodal number of branch on panicle axis. The total number of primary branch and secondary branch per panicle were described both with a quadratic equation. The spikelet number on primary branch and secondary branch changed with nodal point of panicle axis in a linear relationship and a quadratic equation, respectively. The nodal distances of branch on a panicle were described with a power function with nodal points of panicle axis. In addition, the panicle axis space shape curve could be deduced according to panicle axis force balance theory. Furthermore, the effects of nitrogen and water conditions on panicle growth were quantified by the effectiveness values of nitrogen and concentrations in panicle. The model was validated with independent experiment data of different nitrogen rates and water regimes, and the mean RMSEs of panicle length and panicle width were 0.68,0.60,1.18,0.81, respectively.Based on time-course observations on canopy morphological properties under different nitrogen rates and water conditions with four rice cultivars, a dynamic model was developed to simulate time-course growth characters of canopy topological structure on rice plant. The results showed that the canopy topological structure accorded with sigmoid curve, which showed marked differences under different nitrogen rates and water regimes. The growth dynamics of organ elongation could be described with a logistic model and initial elongation GDD and elongation duration GDD of organs was conformed based on the relationship between organ growth time and leaf age, and then a dynamic structural model of rice plant was developed. Meanwhile the rice plant was divided into many parts when the internode and its leaf and panicle were the unit, so the topological structure of rice could be described. The model was validated with the field experiment data of different rice cultivars. The average RMSEs of time-course canopy structure were 11.6%.Based on time-course sampling observations on dry matter partitioning changes at different unit organs of stem and tillers under different nitrogen rates and water regimes with four rice cultivars, a simulation model on dry matter partitioning change dynamics in rice unit organs were developed in relation to GDD, and then the area of single leaf was obtained through simulating single leaf specific leaf weight. The growth dynamics of unit organ partitioning index could be characterized by linear equation and exponent equation respectively (leaf, sheath) and by exponent equation (panicle) in relation to GDD. The change process of the maximum unit partitioning index could be described with exponent equation (unit leaf and unit sheath) and quadratic equation (unit panicle) in relation to different leaf, sheath and panicle position of main stem and tillers. The growth dynamics of specific leaf weight and sheath, panicle dry matter weight of unit organs on stem and tiller could be described with quadratic equation (unit leaf and unit sheath) and power function (unit panicle) in relation to GDD. In addition, the effects of nitrogen and water conditions on dry matter weight and unit partitioning index were quantified through the effectiveness values of nitrogen concentration and water content in unit organs. The model was validated with the independent field experiment data involving different rice cultivars and nitrogen rates. The average RMSEs between the simulated and observed changes at unit organ dry matter weight on main stem and tiller were 0.087, 0.073, 0.53 (leaf, sheath and panicle), respectively.