滴灌条件下华北主要粮食作物耗水特征及节水的生理调控机制

Agriculture is considered as the biggest water consumer in China. Developing high-efficient water-saving agricultural water management is the effective strategy to reducing the total water use and enhancing water use efficient in agriculture. Drip irrigation is considered as a highly water-saving irrigation technique worldwide. To apply this technique in a larger area, it is necessary that we need to get a better understand of the water use characteristics and the mechanism of crop physiological regulation under drip irrigation. Based on long term systematically field experiments and combining theoretical analysis and modeling, researches are planned to be conducted on winter wheat and summer maize, the main crops in China North Plain. We are going make a series of investigations on filed environment and crop growing and physiological factors. The un-even distribution of the soil wetting surface and changed hydrothermal factors caused by drip irrigation need to be considered to separate the soil evaporation and plant transpiration and quantify the ratio of the two components. Those analyses should give us a better understand of water use characteristics. The physiological regulation theory of crops under different drip irrigation and fertilization treatments should be revealed to suggest an optimal water-saving drip irrigation and fertilization regime with plant physiological basis. The spatiotemporal variation and controlling factors of stomatal conductance under drip irrigation will to be quantified first to build a stomatal conductance model based on stomatal regulation theory. The modeling of stomatal conductance should supply the theoretical basis of regulating crop water loss with water-saving irrigation techniques. The expected results are valuable practically and of scientific significance for selecting high-efficient water-saving drip irrigation regimes for grain croplands in China North Plain and revealing the intrinsic advantages of that regime.

农业是我国的用水大户，发展高效节水的农业管理措施是实现控制农业用水总量和提高水分利用效率的有效途径。滴灌是世界上公认的高效节水的灌溉方式，其大面积推广仍需要搞清滴灌条件下作物耗水特征和节水的生理调控机理。基于田间多年连续试验，结合理论分析和模拟，以华北主要粮食作物冬小麦和夏玉米为研究对象，系统观测不同滴灌水肥条件下的农田环境和作物生理指标，综合考虑滴灌引起的土壤表面湿润不均匀及地表水热因子改变等特性，定量区分滴灌条件下农田土壤蒸发和作物蒸腾组分，揭示作物耗水特征和节水生理调控机理，提出具有植物生理理论基础的优化节水滴灌水肥制度；确定不同滴灌水肥处理下气孔导度的时空变异格局及其影响因子，构建基于气孔调节理论的气孔导度模型，为采用节水灌溉措施调控作物水分散失提供理论依据。预期研究成果对我国粮食作物高效灌溉模式的优选及揭示其优异的内在原因具有重要的实用价值和科学意义。

农业是我国的用水大户，高效节水的农业管理措施可显著提高农田水分利用效率。滴灌是世界上公认的高效节水的灌溉方式，其大面积推广仍需要搞清滴灌模式下作物耗水特征和节水的生理调控机理。本研究以华北平原主要粮食作物为对象，对以不同施N量和滴灌水量及覆盖处理为特征的不同滴灌模式对田间蒸发蒸腾及土壤蒸发等影响机理进行了实测和模拟；同时对作物生长、生理、产量和水分利用效率（WUE）等关键指标进行了观测和分析，从光合生理角度明确了作物耗水及产量形成的生理调控机制，提出了适于该地区的优化滴灌制度；基于上述研究，确定了不同滴灌模式下的气孔导度模型参数，并初步实现了气孔导度-光合耦合模拟和验证，具体结论如下：1）滴灌模式下冬小麦全生育期土壤蒸发量（Es）占ET比例在33.0-44.5%之间，夏玉米该比例在17.0-29.6%之间。采用灌水后天数为自变量的Es估算模型，可实现对滴灌条件下冬小麦田Es较为精准的估算。针对夏玉米田，提出了基础作物系数的修正方法，可实现对全生育期玉米田蒸发蒸腾总量的估算。2）不同施N量试验表明：充分滴灌下，该地区每季冬小麦施N量190 kg N hm-2可保持产量不显著降低；不同滴灌水量及覆盖试验表明：以65%-85%的田持作为土壤水分上下限控制的灌溉制度配合秸秆覆盖措施，可保证冬小麦产量相比充分灌水无显著降低，且WUE较高。叶绿素含量（SPAD值）及光合参数可以解释不同滴灌模式之间的产量差异。3）不同滴灌模式显著影响了叶片的气孔导度模型参数和光合参数，参数的处理间差异可用叶片N含量来解释。构建的气孔导度-光合耦合模型能模拟不同滴灌模式下多种因素变化对光合和蒸腾综合影响，从而实现对产量和WUE的预测。本研究结果有利于理解滴灌模式对产量及WUE影响的生理基础，为该地区降低传统施N量和实施科学的滴灌水肥管理和农艺措施提供依据，实现对滴灌模式下华北地区典型农田耗水机理和节水调控理论与技术的创新和突破。