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[目的]研究玉米群体消光系数的动态变化,提高净第一性生产力或产量的准确评估。[方法]基于中国气象局锦州玉米农田生态系统野外观测站2006年玉米生长季(5～9月)的辐射观测数据和叶面积指数动态观测数据,分析玉米群体的消光系数动态变化。[结果]玉米群体生长季消光系数日变化较大,其最大值分别出现在7:00～9:00、15:00～17:00,最小值在12:00前后,但变化幅度在抽雄期变小;在较大的时间尺度上(>5d),消光系数(K)与叶面积指数(LAI)呈抛物线关系,决定系数R2为0.9607。当仅考虑消光系数是太阳高度角或叶面积指数的函数时,方程在模拟玉米群体生长季不同时刻的消光系数K值时准确性较差,为此发展了新的消光系数动态模型K=λ(0.7848-0.0016θ)(0.1548LAI2-0.5586LAI+0.654)。[结论]新的消光系数动态模型综合考虑了太阳高度角和玉米生长季叶面积指数对消光系数的影响,模拟效果优于现有的单因子消光系数模型。
[Objective] The study aimed to study the dynamic change of extinction coefficient of maize population and improve the accurate evaluation of net primary productivity or yield. [Method] The dynamic changes of extinction coefficient of maize population were analyzed based on the observation data of radiation and the leaf area index of 2006 maize growing season (May-September) of Jinzhou maize farmland field observation station in China Meteorological Administration. [Result] The daily variation of extinction coefficient of maize population was larger in the growing season, with the maximum values occurring at 7: 00-9: 00 and 15: 00-17: 00 respectively, with the minimum value around 12:00, but the variation range was at tasseling stage On the larger time scale (> 5d), the extinction coefficient (K) and the leaf area index (LAI) showed a parabolic relationship, and the coefficient of determination R2 was 0.9607. When only the extinction coefficient is considered as a function of solar elevation angle or leaf area index, the accuracy of the equation in simulating the extinction coefficient K of maize population at different times is poor. Therefore, a new dynamic model of extinction coefficient K = λ (0.7848-0.0016θ) (0.1548LAI2-0.5586LAI + 0.654). [Conclusion] The new dynamic model of extinction coefficient comprehensively considered the effect of solar elevation angle and leaf area index of corn growing season on extinction coefficient, and the simulation result was better than the existing single factor extinction coefficient model.