中文摘要：

以2016年山东省禹城市夏玉米为研究对象,通过测定分析不同生长期内降水、土壤水、植物水、地下水、地表水的稳定氢氧同位素值,并利用直接对比法和多元线性混合模型,分析不同水源对夏玉米不同生长期贡献率,进而研究其水分来源。结果表明：禹城市大气降水线方程为δD=7.80δ^18 O＋8.61,其斜率和截距均小于全球大气降水线方程,表明降水在降落过程存在蒸发富集过程。夏玉米不同生长期水分来源存在差异,出苗期由于土壤含水量较低,植物主要利用浅层地下水且利用率为89.6%;拔节期降雨量丰富,夏玉米主要利用0—10cm表层土壤水,利用率为85.8%;抽穗期夏玉米主要利用10—60cm土壤水,利用率达62.9%;生长到灌浆期,根系分布在较深土层且20—100cm土壤含水量稳定,夏玉米主要利用20—100cm土壤水,利用率为69.7%;成熟期植物主要利用大于60cm的深层土壤水,利用率达96.1%,此时期土壤含水量较低且根系分布可达深层土壤。

英文摘要：

In this study,we used hydrogen and oxygen stable isotope tracer technique to determine the water isotopic compositions of precipitation,soil water,groundwater,surface water and xylem water for summer corn during the growing season in 2016 in Yucheng,Shandong Province.Both direct inference approach and multi-source linear mixed models（Iso-Source）were applied to estimate the sources of root water uptake and their contributions in different growing seasons of summer corn.The results showed that the linear model of precipitation wasδD=7.80δ^18 O ＋8.61 for Yucheng,and the intercept and slope were less than the values of global precipitation model due to evaporation.Summer corn mainly used shallow groundwater during the seedling stage and the contribution was 89.6% due to the low soil moisture content.During the rainfallabundant jointing stage,it mainly imbibed water from the 0—10cm soil layer,and the contribution was85.8%.During the heading stage,it mainly imbibed water from the 10—60cm soil layer,and the contribution was 62.9%.The corn mainly used water from deeper soil layer during the filling stage（20—100cm,69.7%）,because the root was in the deep soil layer and soil water content was stable.During the mature stage,it mainly imbibed water from the more than 60 cm soil layer with the low soil moisture content and the deep root,and the contribution was 96.1%.