结构变化和生物量生产与分配过程下苜蓿生长模拟研究

Functional-Structural Model of Alfalfa Based on Dynamical Structure, Biomass Production and Allocation

为真实反映苜蓿的结构和生长过程,经2年土柱栽培试验,对阿尔冈金紫花苜蓿(Medicago sativa‘Algonquin’)的结构和生物量进行动态测定,划分了苜蓿的生长单元。在生长单元上模拟苜蓿的结构变化与不同阶段的生物量生产过程。以生长单元归一化的扩展速率与相应的库强乘积大小作为权重,竞争获取可用的生物量,实现生物量的分配。采用异速生长关系实现苜蓿的几何形态与生物量的动态关联,从而建立苜蓿的功能-结构模型。最后利用第1年的土柱栽培试验获取模型参数,模拟了第2年土柱栽培试验苜蓿同类器官累积生物量的动态变化过程,并对苜蓿生长过程进行可视化仿真。结果表明:不同指标的测定值与模拟值的均方根差值在5.79～123.28g之间变化,相对误差值在0.02～0.67之间变化,模拟值与实测值间有较好的吻合性。所建立的功能-结构模型能够定量化预测苜蓿结构变化与生物量生产及分配的动态反馈过程,从植物生长的机理层次实现苜蓿生长过程的动态模拟。

The functional-structural model of alfalfa was developed based on structure change,biomass production and allocation.The geometrical structures and biomass of each alfalfa organ were measured by two-year field soil culture column experiments.The basic growth unit was determined according to the external morphology of alfalfa.The structures formed by different rank branches were simulated using the structural time scale expressed by thermal time.Based on the spatial morphological structures,the available biomass was calculated by the photosynthetic module which was the function of area of leaves,stems and the average photosynthetic rate each day.The processes of biomass partitioning and accumulation in each organ were completed by the magnitude of sink.Finally,the model parameters were obtained by first-year soil culture column experiments.Results showed that the simulated values agreed with the measured values.The values of RMSE ranged from 5.79 g to 123.28 g,and the values of RE from 0.02 to 0.67 between simulated and measured biomass for different indexes.The model output reflecst the change tendency and growth processes for an alfalfa individual.This suggested that the functional-structural alfalfa model was able to quantitatively predict the feedback process among the structure change,biomass production and partitioning from the mechanism point of development and growth of plant.