小麦苗期根系三维生长动态模型的建立与应用

Development and Application of Three-Dimensional Growth Model of Root System in Wheat Seedling

【目的】构建小麦根系的三维动态模拟模型,并对模型进行初步的评估。【方法】采用GREENLAB植物功能-结构模型的原理,在根系生长发育基本单元基础上,模拟了根系的拓扑结构;通过模拟不同根个体(库)对植株分配给根系的生物量(源)的竞争,实现了生物量在根系中的分配;根据异速生长规则实现了根个体几何结构计算。通过温室土柱栽培试验对小麦苗期根系结构与生物量进行了测定,获取了模型参数,进行了小麦苗期根系结构与生物量分配的模拟与分析,并以三维可视化的方式给出根系的形态结构空间分布。【结果】通过模拟根系生物量在各类根个体中的分配并依据根个体生物量与形态的关系,该模型可以定量化地模拟根系结构生长的动态变化过程;不同类型根的长度测定值与模拟值的均方根差值在1.2～35.0 cm之间变化,相对误差值在0.01到0.23之间变化,R2在0.42～0.94之间变化;对模型参数灵敏性分析表明,模拟结果对参数变化的响应比较适中。【结论】GREENLAB模型的原理可以应用于对作物根系形态结构和生物量分配的动态模拟;模型参数的选择是合理的,构建的模型能够从机理层次反映根系的生长发育过程。

[ Objective ] A development and growth model of wheat root system was developed and evaluated. [ Method] The topological structure was built based on the basic root unit and the principle of GREENLAB model. The biomass partitioning was performed based on the topological structure. It was performed by simulating various basic root units, which are competing for biomass allocated from the plant. The geometrical dimension was calculated using allometrical rules among biomass and root length and volumes of the individual root. Sand culture column experiments in a greenhouse were carried out to measure the structure and biomass of wheat root for calibrating and evaluating the model. [Result]The simulated results showed that the model can be used to describe the structure dynamics homogenous soil＇s wheat root system. The comparison between simulated and measured accumulated root length showed that the value of RMSE ranged from 1.2 cm to 35.0 cm, the value of RE from 0.01 to 0.23, and the value of R2 from 0.42 to 0.94. Most of the simulated values fell within the variance of the measured ones. Sensitivity analysis showed that parameter variations resulted in modest changes in the simulation results. [Conclusion] The principle of GREENLAB plant model can apply to simulate morphology and biomass partitioning of crop root system. The model developed can describe the development and growth process of root systems from mechanical points.