title: Soil water availability and capacity of nitrogen accumulation influence variations of intrinsic water use efficiency in rice.
abstract: Leaf intrinsic water use efficiency (WUEi) coupling maximum assimilation rate (Amax) and transpirable water lost via stomatal conductance (gsc) has been gaining increasing concern in sustainable crop production. Factors that influence leaf Amax and WUEi in rice (Oryza sativa L. cv Unkang) at flooding and rainfed conditions were evaluated. Positive correlations for leaf nitrogen content (Nm) and maximum carboxylation rate (Vcmax), for nitrogen allocation in Rubisco enzymes and mesophyll conductance (gm) were evident independent of cropping cultures. Rainfed rice exhibited enriched canopy leaf average Nm resulting in higher Amax, partially supporting improved leaf WUEi. Maximum WUEi (up to 0.14 μmol mmol(-1)) recorded in rainfed rice under drought conditions resulted from increasing gm/gsc ratio while at cost of significant decline in Amax due to hydraulically constrained gsc. Amax sensitivity related to gsc which was regulated by plant hydraulic conductance. WUEi was tightly correlated to Vcmax/gsc and gm/gsc ratios across the paddy and rainfed not to light environment, morphological and physiological traits, highlighting enhance capacity of Nm accumulation in rainfed rice with gsc at moderately high level similar to paddy rice facilitate optimization in Amax and WUEi while, is challenged by drought-vulnerable plant hydraulic conductance.
authors.affiliation: Department of Plant Ecology, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany; State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 830011 Urumqi, China. Electronic address: xuewei8341@yeah.net.
authors.forename: Wei
authors.initials: W
authors.lastname: Xue
authors.affiliation: Department of Agroecosystem Research, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany.
authors.forename: Bhone
authors.initials: B
authors.lastname: Nay-Htoon
authors.affiliation: Department of Plant Ecology, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany.
authors.forename: Steve
authors.initials: S
authors.lastname: Lindner
authors.affiliation: Department of Agroecosystem Research, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany; Department of Ecosystem Physiology, University of Freiburg, 79085 Freiburg, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Dubbert
authors.affiliation: Department of Plant Ecology, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Otieno
authors.affiliation: Department of Applied Plant Science, Chonnam National University, 500757 Gwangju, South Korea.
authors.forename: Jonghan
authors.initials: J
authors.lastname: Ko
authors.affiliation: Department of Agroecosystem Research, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany; Department of Ecosystem Physiology, University of Freiburg, 79085 Freiburg, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Werner
authors.affiliation: Department of Plant Ecology, BayCEER, University of Bayreuth, 95440, Bayreuth, Germany.
authors.forename: John
authors.initials: J
authors.lastname: Tenhunen
mesh_terms: D055864:Droughts; D008027:Light; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000378:metabolism*
chemical_list: D012987:Soil; D014867:Water; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: Nitrogen; Photosynthesis; Rice; Soil water availability; Stomatal conductance; Water use efficiency