花期高温热害对水稻结实率和产量影响模拟研究

Projected global warming is expected to increase the occurrence of high injury to rice, and pose a serious challenge the rice production and food security in China. Previous studies have show that anthesis/flowering is the most sensitive stage to high temperature. Crop modelling has reported as an important tool to estimate the impacts of climate change on the rice production, but present rice models have seldom attentions on the interaction effect of temperature and duration on spikelet sterility and yield. To cope with this, we aimed to develop a new simple model foo simulating the effects of high temperature on spikelet sterility and yield in rice, which can take accounts into flowering habits, transpisrtional cooling and interaction effect of the temperature and duration. Therefore, fields experiments and the control experiments with different high temperature and with various durations in several cultivars were conducted, and quantitative character istics of rice flowering was cited from the literatures, to quantity the relations between pancile temperature and ambient meteorological data and the relations between temperature×duration interaction and spikelet sterility. It was positive to imrove the ability to simulate the respose of rice to high temperature environment and reduce the uncertainty in effects modelling of climate change on rice with rice models.

水稻抽穗开花期是对高温胁迫最敏感阶段。气候变暖背景下，水稻花期遭遇高温热害的机率增高，花期高温热害成为影响我国水稻产量的重要因素，对粮食安全形成潜在威胁。作物模型作为有效技术工具已被广泛应用于气候变化对农业生产影响研究，但目前绝大多数水稻模型中有关花期高温对颖花结实率与产量影响的模拟较为简化，且未考虑水稻穗温与空气温度间温度差，不能良好反应极端高温对水稻生产的影响。本项目拟在前人水稻花期高温热害研究结果与人工环境控制试验基础上，考虑蒸腾作用对水稻冠层微气候环境影响，建立综合空气温湿度、风速因素的水稻穗温估算模型；研究不同品种类型水稻颖花开花结实动态规律以及不同高温时刻、高温强度、持续时间胁迫条件对其影响，建立花期高温胁迫下水稻颖花结实率与产量模拟模型，以期改善和提高水稻模型对极端高温气候条件的模拟能力，减少模型模拟的不确定性，为水稻高温热害影响评估、适应性对策制定研究打下良好基础。

20世纪全球平均气温已上升了0.6℃，未来50-100年全球气候变化仍将向变暖方向发展，同时极端天气如夏季高温等出现得将更加频繁，且持续时间更长，水稻面更严峻的高温热害挑战。抽穗开花期是对高温胁迫最敏感阶段，花期高温胁迫将导致水稻颖花败育，从而结实率下降，产量降低。现有一些水稻机理模型已经考虑了花期高温对结实率与产量影响，但大多数都是使用了空气温度，而研究表明水稻冠层温度可比周围空气温度低0-4℃，水稻冠层温度能更好的解释温度对开花结实的影响。本研究研究了水稻关键生育期冠层温度与光照、气温、空气相对湿度等气象要素之间的相关关系，基于作物冠层能量平衡原理，建立了以空气温度、湿度、冠层净辐射等为变量的水稻冠层温度模拟模型。基于水稻盆栽试验和文献查阅的基础上, 分析了水稻开花期逐日抽穗量、单穗颖花开花量变化规律，逐日抽穗量、单穗颖花开花量随时间呈泊松(Poisson) 分布，晴朗天气日出后1小时内颖花开放，日出4-5小时到达颖花开放峰值。利用人工气候室盆栽试验观测资料，分析不同高温胁迫处理对水稻结实率的影响，采用产量因素构成法建立产量形成模型，由抽穗开花期日出后6小时内的逐小时冠层最高气温计算温度对开花结实影响。最后耦合水稻生长模型与全球气候模式输出，在站点水平和区域水平分别评估未来气候变暖对中国水稻生产的影响。研究结果用于改善水稻模型在花期高温胁迫下的模拟能力，为气候变化背景下定量模拟和评估高温热害对水稻生长发育及产量形成提供有效工具。