Simulating three-dimensional structure, growth and development of rice plants

水稻产量受形态性状的影响，而形态性状在很大程度上取决于环境和基因型。本研究旨在建立一个模拟水稻植株结构、发育和生长受气候因子和栽培措施影响的模型。整体模型尚未完成，但我们开发的子模型的物候，叶片外观，分蘖，茎伸长，器官的空间分布和冠层中的光环境。根据富山近15年的田间观测资料，检验了基于发育阶段和温度的叶表模型，较好地解释了叶数的年变化。通过模拟温度和株距对分蘖发生概率的影响，建立了不同节位分蘖发生概率的模型。根据在京都和札幌获得的越光的形态学数据，我们观察到，叶片长度的变化之间的位置，年份和N水平是小的叶片，出现在穗分化和以后逐渐变大。CO_2浓度升高对不同基因型的影响不同。叶片尺寸的基因型差异显着的长度：宽度比，但叶片面积可以估计的长度，宽度和一个常数（0.75）的产品为各种基因型。叶片的三维形状可以用12个三角形来近似，用来模拟水稻冠层内的光环境。在光合作用模型中考虑了叶片N和CO_2的影响。这些发现为我们提供了一个工具，以评估冠层光合作用取决于冠层的结构和环境。

Rice productivity is influenced by morphological traits that depend largely on environments and genotypes. The present study aimed to develop a model that simulates rice plant structure, development and growth as affected by climatic factors and cultivation practices. The overall model has not been completed but we developed the submodels of phenology, leaf appearance, tillering, stem elongation, spatial distribution of organs, and light environments in the canopy. The leaf appearance model based on developmental stage and temperature was tested with the field observations in Toyama for the past 15 years and explained well the yearly variation in leaf number. Probability of tiller emergence by node position was developed to simulate the effects of temperature and plant spacing. Based on the morphological data of Koshihikari obtained in Kyoto and Sapporo, we observed that variation in lamina length between locations, years and N levels was small in leaves that appeared before panicle initiation and became progressively larger thereafter. The effect of elevated CO_2 was different among genotypes. Genotypic variation in lamina dimension was marked in length : breadth ratio, but the lamina area could be estimated by a product of length, breadth and a constant (0.75) for various genotypes. Three-dimensional shapes of lamina could well be approximated by 12 triangles, which were used to simulate light environments in the rice canopy. The effects of leaf N and CO_2 were incorporated into the photosynthesis model. These findings provide us with a tool to assess canopy photosynthesis depending on the structure and environments of the canopy.