基于大型称重式蒸渗仪研究北疆滴灌麦田蒸散量

Measurement of Evapotranspiration for Drip-Irrigated Winter Wheat Using Large Weighing Lysimeter in Northern Xinjiang

基于大型称重式蒸渗仪研究了北疆地区滴灌冬小麦不同时段（生育阶段、日、时）的农田水分蒸散特征,分析了气温、相对湿度、风速等因子对农田水分蒸散的影响及产量和蒸散的关系,旨在为北疆地区滴灌冬小麦的灌溉制度制定提供理论依据。3个灌水处理分别为全生育期灌溉375、600和750 mm。结果表明,在滴灌冬小麦全生育期内日蒸散量为抽穗–乳熟〉拔节–抽穗〉乳熟–成熟〉返青–拔节〉播种–越冬〉越冬–返青;在一天中,滴灌冬小麦农田水分蒸散主要发生在8：00–20：00,夜间20：00–8：00蒸散量较小且比较稳定,时蒸散量随天气变化而改变。滴灌条件下,冬小麦的棵间蒸发量占农田水分蒸散的25.2%-28.3%。棵间蒸发与土壤含水率和叶面积指数具有良好的二元二次模拟关系,拟合系数为0.98。综合产量和水分利用效率,滴灌冬小麦的蒸散量为600-650 mm。本研究对合理制定滴灌冬小麦的灌溉制度具有重要的参考价值。

Drip-irrigation is a promising water-saving technique in arid agricultural area. To sep up efficient drip-irrigation systems for winter wheat grown in northern Xinjiang table land, we measured the evapotranspiration（ET） rate of wheat field using large-scale weighing lysimeter and analyzed the temporal responses of ET（in growing phase, daily and hourly） to air temperature, relative humidity and wind speed. Three treatments were designed with irrigation amounts of 375（D1）, 600（D2）, and 750 mm（D3）. During the whole growing period of wheat, daily ET rate varied in different phases, showing heading–milk 〉jointing–heading 〉milk–maturity 〉regreening–jointing 〉sowing–overwintering〉 overwintering–regreening. During a day, hourly ET was in high level from 8：00 to 20：00 and stable from 20：00 to 8：00 of next, which varied with weather condition. Under drip-irrigation condition, the ratio of soil evaporation to ET was 25.2–28.3% during the entire growing season. Soil evaporation could be predicted with soil moisture and leaf area index using a bivariate quadratic function（R^2〉0.98）. Based on a combination of yield and water use efficiency, we suggest 600–650 mm as the optimum irrigation amount under the drip-irrigated winter wheat field.