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Water use efficiency and productive water loss of rice (Oryza Sativa): partitioning seasonal water and carbon fluxes of paddy and rainfed rice

Bhone Nay-Htoon1, Wei Xue2, Maren Dubbert1, Steve Lindner1, John Tenhunen2, Jonghan Ko3, Christiane Werner1
1 Department of Agroecosystem Research, BayCEER, University of Bayreuth
2 Department of Plant Ecology, University of Bayreuth
3 Department of Applied Plant Science, Chonnam National University, ROK.

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02.10.2014, 09:50-10:05, H36, NW III



Agricultural crops play an important role in the global carbon and water cycling process and there is intense research to understand and predict carbon and water fluxes, productivity and water use of cultivated crops under climate change. Mechanistic understanding of the trade of between ecosystem water use efficiency and agronomic water use efficiency to maintain higher crop yield and productive water loss is necessary for the ecosystem sustainability. We studied daily evapotranspiration, transpiration and carbon fluxes of heterogeneous paddy and rainfed rice fields by combing canopy scale gas exchange analysis, crop growth, daily evapotranspiration and transpiration simulation.

According to our findings, evaporation contributed strongly (100% to 75%) to paddy rice evapotranspiration while transpiration of rainfed is almost 50 % of daily evapotranspiration. Canopy transpiration of rainfed rice is mainly controlled by volumetric soil water content and contribution of transpiration to evapotranspiration is significantly higher when the soil water content is lower than field capacity. Although both of ecosystem and agronomic water use efficiency of rainfed is significantly higher than that of paddy rice, significantly lower grain yield and higher respiratory loss of rainfed rice should be considered carefully. Seasonal trend of the contribution of transpiration to evapotranspiration could be an indicator to improve both WUEagro and WUEeco at the same time.

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last modified 2014-09-15