抽穗后高温干旱互作对冬小麦产量形成影响的模拟研究

Climate extreme events, e.g. heat stress and drought stress during reproductive stage have detrimental effects on wheat growth and yield formation. Quantifying the impacts of climate extreme events on wheat production is urgent for early-warning of food security risks in China and worldwide. Process-based crop growth models have become the most widely-used quantitative tools for prediction of crop productivity, but most existing crop models, which showed pool response in predicting the effects of heat stress and drought stress, especially their interactions, on wheat growth and yield formation, need substantial improvement in model mechanism and predictability. Based on a series of wheat pot experiments with different treatments of heat stress, drought stress and their interactions in the artificial climate chamber, this study aims to study the physiological mechanisms of impacts on wheat growth and productivity under different stress combinations. Moreover, based on the exiting experiment and literature data, and by using systematic analysis method and dynamic modelling technology, the dynamic characteristics of growth process, grain development, plant senescence, production of assimilate, distribution of assimilate and yield formation in wheat will be quantified. Furthermore, on the basis of the existing simulation model of wheat growth 'WheatGrow', the simulation model of wheat yield formation under heat stress, drought stress and their interactions during the reproductive stage will be developed. Finally, by integrating with the GIS technology and the scenarios of future climate, the impacts on main wheat production areas in China of post-heading heat stress and drought stress in the future climate conditions can be quantitatively analyzed. The expected results will provide quantitative tools and technical approaches for the security of wheat production in China and the establishment of adaptive strategy in the future climate conditions.

生育后期高温和干旱胁迫等极端气候事件对小麦生长发育和产量形成具有非常不利影响，如何准确定量预测极端气候事件下小麦生产力已成为国内外粮食安全预测预警所迫切需要解决的关键技术之一。基于过程的作物产量形成模拟模型为生产力预测提供了量化工具，但已有作物模拟模型并没有很好体现高温、干旱胁迫及二者互作对作物产量形成影响的生理过程，模型解释性和预测性有待提高。因此，通过在全自动人工气候室实施高温干旱互作处理的小麦盆栽试验，明确不同高温干旱互作对小麦产量形成的影响和生理机制，进一步利用系统分析方法和动态建模技术，基于课题组已有WheatGrow模型，构建抽穗后高温干旱胁迫下小麦产量形成模拟模型，并利用独立年份盆栽和大田高温干旱试验对新建立模型进行校正和检验；最后结合GIS 和未来气候情景，量化未来气候下高温干旱胁迫对我国小麦主产区生产力的影响。研究结果为未来气候下我国小麦安全生产及适应性对策制定提供支撑。

高温和干旱胁迫等极端气候事件对小麦生产力形成具有显著不利影响，迫切需要定量预测极端气候对小麦生产力的影响。基于过程的作物生长模拟模型为生产力预测提供了量化工具，但已有作物模拟模型并没有很好体现高温和干旱胁迫互作对小麦产量形成影响的生理过程，模型的解释性和预测性有待提高。因此，本项目通过在全自动人工气候室实施不同品种、不同时期、不同高温水平和不同干旱程度的高温干旱互作试验，明确了小麦生长发育和产量形成指标在抽穗后高温干旱胁迫互作下的动态变化规律，发现高温和干旱胁迫对小麦光合特征参数存在显著互作效应；在解析小麦蒸腾蒸散和冠层温度对抽穗后高温干旱胁迫互作的生理生态响应机制基础上，基于Penman-Monteith方法和Jarvis模型构建了高温干旱胁迫互作对小麦蒸腾蒸散和冠层温度影响的模型算法；利用独立试验数据对所构建的预测模型进行检验发现，改进后模型对高温干旱互作处理期间的小麦气孔导度、蒸腾蒸散和冠层温度的预测误差分别降低57.14%、22.43%和40.27%，对大田增温试验中小麦产量、穗粒数和粒重的预测误差较原模型分别降低25%、12%和52%；利用改进后的WheatGrow模型，结合不同气候变化情景和GIS技术，量化了基准年代和增温1.5oC、增温2.0oC、RCP8.5情景下高温胁迫对我国冬小麦主产区小麦生产力的影响。结果发现高温胁迫对小麦产量减产效应在我国冬小麦主产区的空间分布表现为显著的“南低北高”特征，不同气候增温情景下所有高温胁迫指标及减产效应的空间分布较为一致，其中在北部冬麦区和黄淮冬麦区高温胁迫在基准年代和未来增温情景下造成的减产损失平均为2.6%、2.1%和3.9%、2.6%。研究结果将为定量预测和评估未来气候条件下我国小麦生产力提供可靠的数字化工具，对于气候变化背景下粮食安全预测预警和应对气候变化的措施制定具有重要意义。