有限灌溉条件下春小麦的蒸散特征及其与产量的关系

针对河西地区农田水资源短缺和水分利用效率较低的问题，利用人工控制灌水的方法研究了春小麦的蒸散量阶段变化特征和日变化特征、蒸散量的影响因子及蒸散量与产量的关系，旨在为该地区小麦水分利用率的提高提供理论依据。结果表明，春小麦阶段蒸散量高峰值集中于灌浆期，占全生育期的41．3％～68．6％，其次为拔节期到抽穗期。不同生育阶段蒸散量的日变化为一单峰曲线，一天中16：00时达最大值，2：00时至6：00时为最低值。回归分析表明，太阳辐射、气温、相对湿度、灌溉定额和土壤含水量是影响蒸散量的主要因子。拔节期至抽穗期蒸散量对产量的影响较大，并与穗粒数和千粒重有很大的相关性。通过用Jensen模型分析生育期不同阶段缺水与产量的敏感程度，以拔节期-抽穗期的敏感指数最大，为0．4238，说明此时期为春小麦需水的临界期。

Evapotranspiration Characteristics and Its Relationships to the Yield of Spring Wheat under Limited Irrigation

To resolving the problem of shorting of water and lower WUE, the stage and daily characteristics of evapotranspiration changes of spring wheat, the influencing factors of evapotranspiration and the relationship between evapotranspiration and crop yield were studied by controled irrigation in this paper. The results showed that the stage of peak evapotranspiration of spring wheat is mainly at grain-filling stage, taking up 41.3 to 68.8 percent of the whole phonological stage, then comes the stage from jointing to heading. The daily change of evapotranspiration at different stages is a single curve. And its highest value is at 4pm , and the lowest value is at 2 to 6 am . Radiation, temperature, irrigation quota and soil moisture content are the main factors that influence evapotranspiration. And the regression models are established respectively, crop yield is influenced greatly by evapotranspiration from jointing to heading, and it is significantly correlated to grain number per ear and 1000-grains weight . Utilizing Jensen model, the paper analyzed the influence of water deficiency on the crop yield at different stages, the period from tassel to mature have the biggest sensitive index of -0. 4238 and this period for the spring wheat is considered as the water demanding criticalperiod.