灌浆期弱光逆境对小麦生长和产量影响的模拟模型

The Simulation Model of the Effects of Low Level of Radiation at Milk Filling Stage on Wheat Growth and Yield

【目的】定量研究灌浆期弱光逆境对弱筋小麦生长和产量的影响,为应对全球气候变化造成的弱光天气事件对小麦生产的不利影响提供决策依据。【方法】以弱筋小麦品种扬麦15号、扬麦13号和宁麦9号为试材,通过设定灌浆期4个光照强度(光照强度分别为自然光强的100%、50%、34%和16%)和4个弱光持续时间(2 d、4 d、6 d和8 d)的遮阴处理试验,模拟连阴雨天气导致的弱光逆境对小麦生长和产量的影响。在定量分析试验数据的基础上,确定弱光逆境对小麦叶片光合作用、叶面积指数和经济系数的影响因子的计算方法。将上述影响因子计算公式与SUCROS模型结合,建立灌浆期弱光逆境影响小麦生长和产量的模拟模型,并使用独立试验资料对模型进行检验。【结果】小麦灌浆期日总光合有效辐射低于3.71 MJ.m-2且持续2 d以上对叶片净光合速率产生显著影响;日总光合有效辐射低于3.71 MJ.m-2且持续4 d以上对叶面积指数、干物质生产和产量产生显著影响。用独立试验资料对模型检验的结果表明,模型对叶片净光合速率、叶面积指数、总干重和产量的模拟值与实测值基于1﹕1线的决定系数(R2)分别为0.78、0.88、0.96、0.96,相对均方根差(rRMSE)分别为5.69%、12.46%、3.32%、5.24%。【结论】本研究建立的模型可以较好地模拟不同强度和持续时间的弱光逆境对小麦灌浆期生长和产量的影响,从而为评估全球气候变化背景下弱光天气事件对小麦生产的不利影响提供了模型工具。

[Objective] In order to assess the impacts of low level of radiation caused by cloudy or rainy weather conditions on wheat crop production, it is necessary to quantify the effects of low level of radiation on wheat growth and yield. [Method] Field experiments with three weak gluten winter wheat （Triticum aestivum L.） cultivars Yangmai 15, Yangmai 13 and Ningmai 9 were conducted during the three growing seasons. Shading treatments with four radiation intensities （100%, 50%, 34% and 16% of natural radiation） and four durations （2 d, 4 d, 6 d and 8 d） at milk filling stage in the three grown seasons were designed to simulate the low level of radiation caused by cloudy or rainy weather conditions. Based on the experimental data, the impacts of low level of radiation on wheat growth processes and yield were quantitatively analyzed, and the impacting factors of low level of radiation on photosynthesis, leaf area index and harvest index were determined, respectively. These functions were then integrated with the SUCROS model to develop a dynamic model for predicting the effects of low level of radiation at milk filling stage on the growth and yield of wheat. Independent experimental data were used to validate the model. [ Result] The critical daily totalphotosynthetically active radiation （PAR） and duration were determined as 3.71 MJ.m-2 and 2 d for leaf net photosynthetic rate; 3.71 MJ.m-2 and 4 d for leaf area index, biomass production and grain yield. Model validation results showed that the determination coefficient （R2） between the predicted and measured values of leaf net photosynthetic rate, leaf area index, total biomass production and grain yield were 0.78, 0.88, 0.96 and 0.96, respectively, and the relative root mean squared error （rRMSE） were 5.69%, 12.46%, 3.32% and 5.24%, respectively. [ Conclusion ] The model developed in this study gave satisfactory predictions of the impacts of low level of radiation at milk filling stage on wheat growth and grain yield, hence, can be used for assessing the impacts of low level of radiation caused by cloudy or rainy weather conditions on wheat production.