低温胁迫下小麦籽粒蛋白质和淀粉形成过程的模拟研究

With global warming, the intensity, frequency and duration of low temperature events are also increasing, which increased the instability of wheat production system and decreased the grain quality of wheat. Therefore, more attention should be paid to study the impact of cold stress on grain quality formation. According to the urgent demand on the prediction of grain protein and starch formation under low temperature condition, a series of wheat pot experiments under different low temperature treatment stages, levels and durations were carried out below the daily variation rule of natural temperature in the artificial climate chamber. The objectives of this study were to investigate the dynamic mechanism of carbon and nitrogen composition, accumulation and transportion under low temperature stress in different organs, to illuminate the variation of grain quality with the low temperature treatments, and quantify the relationship between the processes of carbon and nitrogen accumulation, grain protein and starch formation and air temperature and canopy temperature. Furthermore, on the basis of system analysis method, dynamic modeling technology and the existing simulation model 'WheatGrow', the grain protein and starch formation model of wheat under low temperature stresses will be developed. Finally, the model will be tested and evaluated with the field experiments and independent chamber experiments under low temperature stress. The results will provide quantitative tools and technical approaches for wheat grain quality prediction and evaluation, and the high quality wheat production management and regulation under the future climate conditions.

随着全球变暖，低温发生的强度、频率和持续时间也在不断加强。低温的频发加剧了小麦生产系统的不稳定性，降低了小麦籽粒的品质。因此，低温胁迫下小麦籽粒品质形成的研究至关重要。本研究针对低温胁迫下小麦籽粒蛋白质和淀粉形成过程定量预测的迫切需求，通过在人工气候室实施自然温度日变化模式下的小麦试验，解析不同低温处理下小麦各器官碳/氮合成、积累、转运的动力学机制及籽粒蛋白质和淀粉及其组分形成随低温处理的变化规律，量化低温胁迫下植株碳/氮转运、籽粒蛋白质和淀粉形成过程与大气及冠层温度变化的动态关系，基于已有的小麦生长模型WheatGrow，构建低温胁迫下基于植株碳/氮流的小麦籽粒蛋白质和淀粉形成模拟模型，并利用独立的低温胁迫下的小麦大田和人工气候室资料，对所建模型进行检验和完善。研究结果将为气候变化条件下小麦籽粒品质的预测与评价、优质小麦生产的管理与调控等提供量化工具与技术途径。

随着经济的发展和人民生活水平的提高，小麦籽粒品质越来越为人们所关注。小麦品质是一个复杂的综合性状，不仅由品种特性决定，还受到环境条件的影响，而在环境因素中又以温度的影响最为突出。随着全球气候变暖，小麦春季遭受冷害的频率和强度也在不断上升，加剧了小麦生产系统的不稳定性，降低了小麦籽粒的品质。因此，迫切需要深入分析并量化低温胁迫对小麦籽粒品质形成的影响，完善作物生长模型对低温胁迫的响应和预测能力。本研究首先在人工气候室中对温度敏感性不同的两个小麦品种，分别在拔节期、灌浆期及拔节和灌浆双期实施了自然温度日变化规律下不同低温强度和低温持续时间的小麦盆栽实验，解析了不同低温处理下小麦各器官碳/氮积累、分配与转运的动力学机制及籽粒蛋白质和淀粉及其组分形成随低温处理的变化规律，结果发现低温显著降低小麦的干物质积累和收获指数，影响植株干物质的分配和转运。随着温度的下降和低温持续时间的延长，小麦籽粒总蛋白、球蛋白均呈显著上升趋势，而总淀粉及其组分含量则呈显著的下降趋势；基于小麦低温试验数据，量化了低温胁迫下植株碳/氮积累与转运、籽粒蛋白质和淀粉形成与温度间的动态关系，结果发现随累积低温度日的增加，小麦的收获指数、花前营养器官干物质转运量、花后干物质积累量以及籽粒蛋白质和淀粉积累的特征参数均显著降低；结合已有的WheatGrow模型，构建了低温胁迫对小麦籽粒蛋白质和淀粉形成的模拟算法。检验结果表明改进后的WheatGrow模型在低温胁迫下具有较好的模拟能力。研究结果可为气候变化条件下小麦籽粒品质的预测与评价、优质小麦生产的管理与调控等提供量化工具与技术途径。