CO2浓度和温度互作对水稻开花和灌浆过程的影响机制及其调控

The rising atmospheric CO2 concentration and its concomitant global warming are two main characteristics of climate change. Abundant evidence from the previous chamber studies indicate that high temperature stress can decrease CO2 fertilizer effect and even cause yield reduction in sever scenarios. This well recognized negative CO2 concentration by air temperature interaction will pose a direct threat to current and future world rice production. Rice at flowering and grain filling stages are very sensitive to high temperature, which often occurs during the crucial reproductive period in large rice production area. The high-temperature induced inhibition of CO2 fertilizer effect in rice is very likely associated with the responses of these two key processes to CO2 and temperature. We will use the experimental platforms with fumigation environment close to natural farmland, and treat rice plants during the whole growth period with elevated atmospheric CO2 concentration and temperature that simulates the rice growth environment in the middle of this century. In order to find a method to maintain or increase rice productivity under the scenario of climate change, we will investigate the effects of high CO2 concentration and/or high temperature on grain-filling capacity and yield formation of rice and its agronomic regulation approaches, and study the influences of high CO2 and/or high temperature on rice flowering and grain filling processes and its physiological mechanisms. The results will greatly increase our capacity in predicting rice response to future high-CO2 and high-temperature world, and will be useful for the effective preparation of adaptation strategies for future rice production.

迅速增加的大气CO2浓度增高及其伴随的全球变暖是气候变化的两个主要特征。前期大量气室研究发现，高温胁迫使高CO2浓度对水稻产量的肥料效应减小甚至造成减产，这种广泛报道的负向互作将直接威胁当前和未来世界的稻作生产。水稻开花和结实过程对经常同期而至的高温胁迫非常敏感，高温胁迫抑制CO2的肥料效应很可能与这两个关键过程的应答有关。利用熏蒸环境接近于稻田的试验平台，全生育期动态模拟本世纪中叶大气CO2浓度（增200 μmol mol-1）和温度（增2℃），设置多因子互作试验，研明高CO2浓度和高温对水稻结实能力和产量形成的影响及其农艺调控途径，揭示这两个重要环境因子对水稻开花受精和灌浆结实过程的影响及其生理基础，探索气候变化情形下增加或维持水稻生产力的途径和方法。阐明这些问题将显著增强我们对未来高CO2浓度和高温环境下水稻响应的预测能力，进而更加有效地制订出应对气候变化的适应策略。

大气CO2浓度和气温升高是气候变化的两个主要特征。水稻是人类最重要的食物来源，研明CO2浓度、温度特别是两者的交互作用对水稻的影响对世界或地区粮食安全均很重要，但迄今为止两因子的互作研究较少，更缺乏自然农田环境中的开放式试验研究。全球变暖给稻米生产带来威胁，特别是当高温胁迫与开花受精和籽粒灌浆过程同期而至的情形下。本项目主要利用稻田 FACE平台，模拟本世纪中叶的大气CO2浓度和温度，重点研究代表性水稻品种结实和产量性状对CO2浓度的响应及其与冠层气温变化的关系。结果表明，对高温较为钝感的籼型品种而言，高温处理下大气CO2浓度升高使水稻增产的幅度大于环境温度处理（+64% vs +39%），饱粒率、秕粒率、空粒率以及平均粒重等结实性状的变化均表现出相似趋势。这主要与高浓度CO2环境下生长的水稻能维持较高的碳水化合物生产水平，进而可有效减轻高温对花粉发育和籽粒灌浆的伤害。相反，对高温较为敏感的粳型水稻而言，CO2浓度与温度互作对颖花育性和充实过程均有负面影响；表现在高CO2浓度环境下每穗颖花数和饱粒率降低，垩白增加，但开花期遭遇高温会恶化这种负面影响，进而降低CO2对产量的肥料效应。除了品种之外，CO2浓度或/和温度处理的效应也依赖于籽粒着生位置、栽培措施和环境条件。以上研究结果可为准确预测气候变化对我国稻作生产的影响以及制定适应对策提供参考。项目实施期间研究小组发表标注基金资助的相关论文16篇，其中SCI收录3篇、CSCD收录论文13篇；另外，指导完成博士后出站报告1篇、硕士毕业论文4篇。

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