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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2018-234
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
14 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Seasonal variability in evapotranspiration partitioning and its relationship with crop development and water use efficiency of winter wheat
Ying Ma1, Praveen Kumar2, and Xianfang Song1 1Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
2Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, IL, USA
Abstract. The partitioning of evapotranspiration (ET) into soil evaporation (E) and crop transpiration (T) is fundamental for accurately monitoring agro-hydrological processes, assessing crop productivity, and optimizing water management practices. In this study, the isotope tracing technique was used to partition ET and quantify the root water uptake sources of winter wheat during the 2014 and 2015 growing seasons in Beijing, China. The correlations between seasonal ET partitioning and the leaf area index (LAI), grain yield, and water use efficiency (WUE) were investigated. The fraction of T in ET (FT) between the greening and harvest seasons was 0.82 on average and did not vary significantly among the different irrigation and fertilization treatments (p > 0.05). However, the values of FT during the individual growth periods were remarkably distinct (ranging from 0.51 to 0.98) among the treatments. The seasonal variability in FT could be effectively explained via a power-law function of the LAI (FT = 0.61 LAI0.21, R2 = 0.66, p < 0.01). There was no significant relationship between FT and the grain yield or WUE (p > 0.05). The total T during the jointing–heading and heading–filling periods (Tjf) had significantly quadratic relationships with the crop yield and WUE (p < 0.01). Both the crop yield and the WUE had high values under the Tjf range of 117.5–155.8 mm. Furthermore, the WUE was improved by increasing the ratio of E in ET (FE) during the greening–jointing period and by reducing FE during the filling–harvest period. Winter wheat mainly utilized soil water from the 0–20 cm (67.0 %), 20–70 cm (42.0 %), 0–20 cm (38.7 %), and 20–70 cm (34.9 %) layers during the greening–jointing, jointing–heading, heading–filling, and filling–harvest periods, respectively. This indicated that the irrigation wetting layer should be controlled at depth of 70 cm to conserve water.
Citation: Ma, Y., Kumar, P., and Song, X.: Seasonal variability in evapotranspiration partitioning and its relationship with crop development and water use efficiency of winter wheat, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-234, in review, 2018.
Ying Ma et al.
Ying Ma et al.
Ying Ma et al.

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Short summary
This study determined the seasonal variations in ET partitioning and root water uptake sources of winter wheat via the isotope tracing technique. The correlations between ET partitioning and LAI, grain yield and WUE were investigated. The seasonal change in fraction of T in ET could be effectively described as a power-law function of LAI. The total T during the jointing–heading and heading–filling periods had a significant quadratic relationship with grain yield and WUE.
This study determined the seasonal variations in ET partitioning and root water uptake sources...
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