高温胁迫对水稻关键生育期的影响及其模拟

Heat stress affects rice growth and development, but the adverse effect on rice development can’t be correctly estimated by most rice phenological models, which results in large errors in rice development simulations and also influences the simulation of other physiological process that depends on the rice development. By field experiments and mathematical modelling methods, this project intends to study the influence of heat stress on rice development in key rice phenological stages, and to improved rice phenological models in rice development simulations under heat stress. To achieve this, a standard rice phenological scale and coding system is first introduced to standardize the observation of rice phenological development. It is also used to establish a quantitative relationship between the coded scale and simulated physiological development time. After that, the variation of the air temperature at 2 m height above paddy surface, the temperature of paddy water layer as well as that of rice canopy is analyzed with the analysis of their mutual relationships. Meanwhile, with statistical analysis methods, key temperature factor during the heat stress period is approved, and with the mathematical modeling strategy, heat stress influential function is established; Then, with model coupling methods, the quantitative relationship and heat stress influential function are coupled into rice phenological models, which is able to improve the simulation of rice development under heat stress. Finally, data assimilation is applied to put forward a dynamic assessment method for heat stress. This study not only establishes the simulation method to account for the influence of heat stress on rice development, but also provides a technical reference for the accurate assessment of the influence of heat stress in future climate change.

高温胁迫影响水稻生长发育，但现有的水稻生育期模型无法就高温胁迫作用做出正确响应，导致发育期模拟错误并影响其他水稻生理进程的模拟。该项目拟运用田间试验和数学建模相结合的方法，研究高温胁迫对水稻关键生育期发育进程的影响，通过改进生育期模型实现高温胁迫影响的模拟。首先，引入国际通用水稻物候期划分标准和编码，规范生育期观测，建立生育期编码与模拟的生理发育时间的定量等换关系；然后，分析高温胁迫时稻田气温、水层温度和冠层温度的变化规律及相互关系，采用统计分析方法，确立高温胁迫下的主导温度因子，并结合数学建模技术，构建高温胁迫影响函数；采用模型耦合技术，将编码定量等换关系和高温胁迫影响函数引入水稻生育期模型中，通过改进模型实现高温胁迫下发育进程的准确模拟。最后，应用数据同化技术，提出高温胁迫影响的动态评估方法。该项研究不但建立了高温胁迫影响的模拟方法，还为准确评估未来气候变化下高温胁迫影响提供技术参考。

课题以水稻生育期为落点，从试验到建模，再到应对措施的验证，较全面地掌握了高温胁迫影响生育期的事实和影响机制，提出了应对技术，开发了生育期高温热害影响预报系统，相关成果在浙江省得到应用和推广。.主要研究内容：.（1）研究区水稻高温热害发生规律和特征：分析了水稻高温热害的发生规律和变化特征，为研究区的选定和实验品种的确定提供依据。.（2）实验观测和数学建模：建立多层的网格化温湿度观测平台，实时获取土壤、水层、冠层的环境数据，分析了高温下各要素的时序、强度变化特征。.（3）高温热害对生育期和生长要素的影响：确定了关键的高温热害因子和作用时段，构建了高温热害对关键生育期和生长量的影响模型。.（4）关键生育期高温热害应对措施：通过调节灌溉、喷施化学药剂等试验方法，确定缓解高温热害影响的有效措施。.（5）高温热害影响的系统开发和应用验证：开发了水稻高温热害监测业务系统，在一线业务单位得到应用和推广。.重要结果：.（1）长江以南地区是水稻高温热害的主发区和频发区，主要发生在拔节至抽穗期间，生育期平均缩短1-3天，影响穗器官的形成和生长。.（2）水稻封行后，相比土温和水温，冠温是影响水稻生育期发展的最关键因素。使用冠层温度模拟高温影响比2米气象温度精度更高。.（3）支持向量机模型对水稻冠层温度模拟精度较高，绝对误差约1℃。Beta函数在模拟高温热害对生育期影响的精度明显优于双线性和Blackman函数，模拟误差在3－8天。.（4）井水灌溉和喷施合理量的化学制剂对缓解高温热害影响明显。尽管对生育期的影响不明显，但对光合作用、干物质积累和分配高温缓解作用显著。.课题共发表论文13篇，其中SCI收录2篇。获6项计算机软件著作权，发明专利1个。中国气象局成果鉴定1项。科研奖励2项。培养硕士研究生8名。.该项研究不但揭示了高温胁迫对水稻生育期和干物质生长的影响，还为研究持续气候变暖下水稻高温胁迫影响提供技术参考。