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 was δD=7.80 δ18O +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 rainfall-abundant jointing stage

it mainly imbibed water from the 0—10 cm soil layer

and the contribution was 85.8%. During the heading stage

it mainly imbibed water from the 10—60 cm soil layer，and the contribution was 62.9%. The corn mainly used water from deeper soil layer during the filling stage (20—100 cm

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%.