Abstract:  A model for canopy light distribution in rice was developed by integrating certain advantages in existing models, and then a processbased photosynthetic production model was furtherly developed by integrating the canopy light distribution model   with the rice photosynthesis. The rice canopy was   divided into five layers according to leaf area index. Solar radiant intensity on horizontal plane at each layer was calculated by MonsiSaeki exponential model. The direct and diffuse radiations were calculated from the local meteorological data of sunshine duration, while the diurnal variation of photosynthetically active rediation  and the influence of direct radiation extinction coefficient on both canopy structure and solar position were also considered. Preliminary validation of canopy light distribution model with independent field experiment datasets showed that the model could accurately predict canopy light distribution under different growing environments. The RMSE(root mean square error) of predicting in rice dry weight for canopylightdistributionbased model and  an  existing model were 0.74  t/hm2  and 1.26  t/hm2, respectively,   indicating  that the canopylightdistributionbased  model   had a better performance.  This study would further play an important role in improvement of rice growth model, rice production management and regulation and variety digital design.

Key words: rice, light distribution, photosynthesis, dry matter accumulation, simulation model

摘要： 综合已有作物模型的优点，构建了水稻冠层光分布模型，并进一步与原有光合作用和干物质生产模型相耦合，构建了水稻光合生产模型。新模型将水稻冠层按叶面积指数划分为5层，各层次水平面上的太阳辐射强度按Monsi和Saeki的指数模型进行分布；模型利用日照百分率资料推算直接辐射与散射辐射，并考虑了光合有效辐射的日变化、冠层结构和太阳位置对直接辐射消光系数的影响。利用独立的水稻田间试验资料，对主要生育期冠层内的光分布进行了初步验证，结果表明模拟值与观测值之间具有较好的一致性。最后，将基于冠层光分布模型与原有光合生产模型进行了比较，预测水稻干物质积累量的根均方差分别为0.74 t/hm2和1.26 t/hm2，建立的基于冠层光分布模型的预测性较好。研究结果将为水稻生长模型的改进完善以及生产管理调控与品种数字化设计奠定基础。

关键词: 水稻, 光分布, 光合作用, 干物质积累, 模拟模型