作物高效用水的气孔和水力协同调控机理与模拟

Crop efficient water use is a fundamental research problem in contemporary agricultural water science, and involves multiple coupled nonlinear processes of matter and energy exchanges. However, the mechanism of the physiological controls of crop efficient water use remains largely elusive. The proposed project will focus on understanding the mechanisms of the coordinating controls of crop efficient water use by stomatal and hydraulic conductances, and build quantitative model depicting the associated transport processes. The comprehensive measurements of crop water use and ecophysiological and environmental factors will be conducted for maize under water deficits at different spatiotemporal scales. The variations of crop water use will be explored at the different spatiotemporal scales. The variations and differences of crop water use for different treatments will be examined. The controlling factors and response thresholds of crop efficient water use to its control factors will determined. The responses of stomatal and hydraulic conductances to environment factors will be investigated using the measured or calculated measurements. The variations of stomatal conductance and its responses to environmental factors will analyzed. The regulation of chemical signaling on stomata will be determined. By analyzing decoupling coefficients of crop water use and atmosphere, the effect of hydraulic structures on the sensitivity of the response of stomatal conductance to atmospheric evaporation demand will quantified. Based on the status of leaf water potentials and drought signals, the isohydric and anisohydric behaviors of stomatal regulation will be recognized. The interaction mechanisms of stomatal and hydraulic conductances will be explored. Thus, the mechanisms of the coordinated controls of efficient crop water use by stomatal and hydraulic conductances will be understood through quantifying the effect of hydraulic conductance on the sensitivity of stomatal conductance to vapor pressure deficit. Based on the above understanding, an integrated mechanistic model of coupling multi-process of crop efficient water use will be developed, incorporating controls of stomatal and hydraulic conductances, physiological responses, canopy radiative transfer, leaf energy budget, turbulence transport and soil water and heat transfer. Therefore, the project will enhance the understanding the mechanisms of crop efficient water use.

作物高效用水涉及复杂的物质与能量过程，是当代农业水利学中一个基础科学问题，但它的生理调控机理尚不清楚。本项目以深入认识作物高效用水的气孔和水力协同调控机理并建立定量模型为主线；选择玉米为研究对象，通过对不同水分亏缺下多时空尺度作物用水与生理生态和环境因子综合观测，揭示作物用水的变化特征和差异，识别作物高效用水的主控因子和响应阈值；分析气孔导度变化特征及其对环境因子的响应关系，探究化学信号对气孔导度的调节作用；量化作物用水与大气的耦合程度，明确气孔对作物用水的动态调控机理；依据叶水势和干旱信号，判别气孔调节的等水或非等水行为；揭示水力导度与气孔导度的互馈机制；量化水力导度对气孔导度与水汽压亏缺响应敏感性因子的影响，理解其协同调控作物高效用水的机理；建立耦合气孔和水力调控、生理响应、辐射传输、能量平衡、湍流传输和土壤水热运移等多过程的作物高效用水机理集成模型，提升农业高效用水理论的认识水平。

围绕深入认识作物高效用水的气孔和水力协同调控机理并建立定量模型为主线，以玉米和番茄为研究对象，通过对不同水分和盐分胁迫下多时空尺度作物用水与生理生态和环境因子综合观测，揭示了作物用水的变化特征和差异，识别了作物高效用水的主控因子和响应阈值；发现水盐胁迫下气孔和叶肉扩散限制是番茄光合速率的主要限制因子，占比84.6%~89.0%；分析了气孔导度变化特征及其对环境因子的响应关系，探究了化学信号对气孔导度的调节作用；发现水盐胁迫下最大气孔密度受面积调控，气孔导度受ABA和叶水势协同调控；量化了作物用水与大气的耦合程度，明确了气孔对作物用水的动态调控机理；揭示了水力导度与气孔导度的互馈机制；建立了水力和气孔协同调控作物高效用水集成模型。在试验研究与理论分析的基础上，依托本项目共发表学术论文5篇，其中SCI收录论文4篇；获发明专利1件，申请发明专利1件；参编专著1部（撰写8.15万字）。发表在Agricultural Water Management（2017, 179: 122-131）的论文为2018年高被引论文。项目负责人参加完成的“创建‘五链环’野外综合实训平台与‘四融合’人才培养模式的探索及其实践”荣获第三届中国学位与研究生教育学会研究生教育成果唯一的特等奖（第5），参加完成的“西北旱区制种玉米水热通量监测与模拟及综合调控模式”成果获中国农业节水和农村供水技术协会一等奖（排名第2）。项目负责人参加了3次农业高效用水创新引智基地（111计划）学术研讨会、“第三届石羊河论坛暨水与绿色发展学术研讨会”和“中国农业工程学会农业水土工程专业委员会第十届学术研讨会”，并作学术报告，并到美国伊利诺伊大学香槟分校访问交流1年。依托本项目，培养了2位博士、7位硕士、6位学士；目前在读2位博士研究生、3位硕士研究生、5位本科生参与了该项目研究。通过本项目提升了农业高效用水理论的认识水平，为提高作物高效用水管理提供了一定的科学依据。结合其他项目，在石羊河流域进行了作物需水量和节水节肥高效灌溉模式的技术示范推广，向当地基层技术人员和农民推广农业节水技术和最新研究成果，科学有效地服务当地节水高效农业发展。