小麦水分利用和产量形成对水分亏缺响应的区域差异与节水灌溉机制

In the Northern Winter Wheat Region, the precipitation during wheat growing can only meet the demand of 20%~30% of Wheat. The high grain yield of wheat mainly depends on groundwater for irrigation. Now, as the over exploitation of groundwater have become increasingly serious, there is an urgent need for the traditional “setting irrigation water according to yield goal” change to “setting yield goal according available irrigation water” in the irrigation and water regulation study in wheat. So to improve water use efficiency without a substantial decrease in yield, and stabilize the area and yield of wheat, which has important significance to guarantee the food security in China..Because the water resources in Northern Winter Wheat Region exists significant difference in spatial and temporal demission, the project will be carried out in the typical wheat regions with significantly different water resources in Hebei (with annually precipitation of 500mm and 120mm during wheat growing) and Shandong (680mm/180mm) respectively, and the techniques of field water-control experiments, physiological and biochemical experiments in laboratory, soil water balance model and spatial scale expansion will be used. From the perspectives of the relationship of grain yield, water consumption and water use efficiency, moisture migration law in Soil-Plant-Atmosphere Continuum, photosynthetic material synthesis, accumulation and translocation, the enzymatic regulation and hormone regulation of key process of yield formation in wheat, the response mechanism of yield formation and water use to water deficit and irrigation will be researched, and the regional differences will be revealed. Based on the experiment study and model simulation the project will provide optimal combination of yield and water use efficiency based on the spatial and temporal distribution of water deficit. The results will provide important scientific foundation for water saving irrigation in the Northern Winter Wheat Region in China.

北方冬小麦生育期间降水仅能满足小麦需求的20%~30%，小麦高产有赖于地下水灌溉。当前地下水超采严重，小麦水分调控思路迫切需要由传统“以产定水”向“以水定产”改变，在不显著降低产量的同时，提高水分利用效率，对稳定小麦面积和产量，保障粮食安全意义重大。基于北方冬麦区水资源存在显著时空变异，本项目拟在河北（年降水500mm/小麦生育期间降水120mm）和山东（680mm/180mm）水资源存在差异的典型麦区，利用田间水分控制试验、室内生理生化试验、土壤水量平衡模型和空间尺度拓展，从产量、耗水量和水分利用效率的关系、土壤-植株-大气中水分运移规律、小麦光合物质合成与转运、小麦产量形成关键过程的酶学调控和激素调控等角度，研究不同水资源条件下小麦水分利用和产量形成对水分亏缺和灌溉的响应机制与区域差异，提出基于水分亏缺时空分布的产量和水分利用效率最优组合，为北方冬麦区节水灌溉提供重要科学依据。

北方冬小麦高产有赖于地下水灌溉，优化灌溉调控技术，在保证高产的同时，提高水分利用效率，对实现绿色发展、保障粮食安全意义重大。于2016-2019年三个小麦生长季在山东和河北水资源存在差异的典型冬麦区布设了多点位不同水分亏缺程度的田间试验，通过大田试验测定、生理生化分析，研究了降水与土壤水分和小麦耗水的关系，探究了水分运移和小麦产量形成对水分亏缺和灌溉的响应机制，提出小麦高产节水灌溉的优化方案。研究发现：（1）山东和河北麦田耗水量一般在360-500mm，其中约34-40%来自降水，39-60%来自土壤贮水。与充足灌水相比，适度水分亏缺下，灌水量和总耗水量低，灌浆期的阶段耗水量和棵间蒸发量低，灌浆中后期旗叶水势、土壤水势、土壤贮水消耗量高，土壤-植株-大气中水分运转效率高。（2）适度水分亏缺下，小麦灌浆中后期旗叶净光合速率、气孔导度、旗叶水分利用效率和磷酸蔗糖合成酶活性高，旗叶最大光化学效率、PSII系统光化学活性、光化学猝灭系数等高，旗叶光合功能期长，光能转化率高；灌浆中后期籽粒灌浆速率高，成熟期干物质积累量高，开花后营养器官贮藏同化物向籽粒的分配高，有利于增加粒重，提高籽粒产量。（3）1960年以来不同时间尺度的标准化降水蒸散发指数显示，河北和山东冬小麦生长季的干旱状况趋于加重，重度和极端干旱频率增加，越冬期、生育后期和整个生长季SPEI指数与冬小麦产量波动呈正相关关系。（4）关键时期严重水分亏缺导致显著减产；灌水处理的水分利用效率高于不灌水处理，随灌水量增大，水分利用效率和灌溉效益下降，适度水分亏缺，即拔节期和开花期通过灌水调节0-40cm土层土壤相对含水量为70%~75%（山东试验点）或75%~80%（河北试验点），能得到高产和高水分利用效率的相对统一。现代农业节水理念提倡以尽可能少的水资源消耗获得尽可能多的粮食产量，本研究结果有利于更准确认识作物水分利用和产量形成对不同程度水分亏缺的响应，为制定合理灌溉决策提供科学依据和数据支持。