不同品种和氮素条件下水稻茎鞘夹角动态模拟

 【目的】建立水稻主茎上不同叶位叶片茎鞘夹角动态变化的模拟模型。【方法】基于不同株型品种和氮肥处理的水稻试验，连续观察并记录各处理不同生育时期、不同叶位的茎鞘夹角，进一步利用动态建模技术构建水稻主茎不同叶位茎鞘夹角的动态模拟模型。【结果】水稻茎鞘夹角随生长度日（GDD）不断加大，夹角从开始形成到基本稳定大致经历3个叶龄，且随氮肥施用量的增加而增大；最大茎鞘夹角随叶位的增加呈先增加后减小的趋势，第三叶的最大茎鞘夹角最大。利用Logistic方程可以描述不同品种、不同氮肥处理下，水稻茎鞘夹角随GDD的变化过程，使用直线型分段函数可以描述最大茎鞘夹角随叶位的动态变化规律，通过引入品种参数（第三叶位茎鞘夹角的最大值）量化了品种对茎鞘夹角的影响，同时在模型中添加氮素影响因子来体现氮素对茎鞘夹角的影响。【结论】利用独立的桶栽和池栽试验数据分别对模型进行检验，结果显示茎鞘夹角模拟值与观测值之间的均方根差RMSE分别为2.31°和2.87°；相对均方根差RRMSE分别为11.56%和14.77%，表明模型对水稻主茎茎鞘夹角的动态变化过程具有较好的预测性，可为水稻植株的可视化提供良好的技术支撑。

Dynamic Simulation on Angle Between Stem and Sheath in Different Rice Cultivars and Nitrogen Rates

【Objective】The objective of this paper is to develop a dynamic simulation model on angle between stem and sheath at different leaf positions on main stem in different rice cultivars and nitrogen application rates.【Method】Based on rice experiments with different cultivars and nitrogen rates, the values of angel between stem and sheath of different leaf positions on main stem during different development stages were continuously observed, a dynamic simulation model for changes of angle between sheath and stem at different leaf positions on main stem was developed by using dynamic modeling technology. 【Result】 Rice angle between stem and sheath increased with leaf development progress, the duration from the beginning of angle formation to the maximal value was about three leaf ages and the angles increased with the increasing nitrogen rates. From the first leaf to the third leaf, the maximum angle between stem and sheath at each leaf position increased with the increasing leaf position, and then decreased with the increase of leaf position. The logistic equation could be used to describe the change process of the angle between stem and sheath on main stem with growing degree days (GDD) in different varieties and nitrogen rates, and the maximum angle between stem and sheath with leaf position on main stem could be described with linear piecewise function. A variety parameter (the maximum angle between stem and sheath at the third leaf position) was introduced to quantify the variety characteristics on the angle between stem and sheath. Nitrogen factor was also used to reflect the effect of nitrogen on the angle between stem and sheath. 【Conclusion】A set of independent pot and pool experiments data were used to test the model, and the root mean square error (RMSE) between observed and simulated values was 2.31° and 2.78°, respectively, and the relative RMSE (RRMSE) was 11.56% and 14.77%, respectively, which indicated that the model has a good performance on predicting the angle between stem and sheath at different leaf positions on main stem. These results would provide technological support for the visualization of rice plant.