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Title: Unsaturation of vapour pressure inside leaves of two conifer species

Abstract

Stomatal conductance (g s) impacts both photosynthesis and transpiration, and is therefore fundamental to the global carbon and water cycles, food production, and ecosystem services. Mathematical models provide the primary means of analysing this important leaf gas exchange parameter. A nearly universal assumption in such models is that the vapour pressure inside leaves (e i) remains saturated under all conditions. The validity of this assumption has not been well tested, because so far e i cannot be measured directly. Here, we test this assumption using a novel technique, based on coupled measurements of leaf gas exchange and the stable isotope compositions of CO 2 and water vapour passing over the leaf. We applied this technique to mature individuals of two semiarid conifer species. In both species, e i routinely dropped below saturation when leaves were exposed to moderate to high air vapour pressure deficits. Typical values of relative humidity in the intercellular air spaces were as low 0.9 in Juniperus monosperma and 0.8 in Pinus edulis. These departures of e i from saturation caused significant biases in calculations of g s and the intercellular CO 2 concentration. Thus, our results refute the longstanding assumption of saturated vapour pressure in plantmore » leaves under all conditions.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [5];  [5];  [6]; ORCiD logo [5];  [2];  [7];  [2]
  1. James Cook Univ., Cairns, QLD (Australia). College of Science and Engineering
  2. Australian National Univ., Canberra, ACT (Australia). Research School of Biology
  3. Univ. of California, Santa Cruz, CA (United States). Dept. of Ecology and Evolutionary Biology
  4. METER Group, Inc., Pullman, WA (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Biology
  7. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Earth Systems Analysis and Modelling Group
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1440441
Report Number(s):
LA-UR-17-30329
Journal ID: ISSN 2045-2322
Grant/Contract Number:  
AC52-06NA25396; DP1097276; DP150100588
Resource Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; Biological Science; stomatal control, leaf gas exchange, pinon, juniper, drought

Citation Formats

Cernusak, Lucas A., Ubierna, Nerea, Jenkins, Michael W., Garrity, Steven R., Rahn, Thom, Powers, Heath H., Hanson, David T., Sevanto, Sanna, Wong, Suan Chin, McDowell, Nate G., and Farquhar, Graham D. Unsaturation of vapour pressure inside leaves of two conifer species. United States: N. p., 2018. Web. doi:10.1038/s41598-018-25838-2.
Cernusak, Lucas A., Ubierna, Nerea, Jenkins, Michael W., Garrity, Steven R., Rahn, Thom, Powers, Heath H., Hanson, David T., Sevanto, Sanna, Wong, Suan Chin, McDowell, Nate G., & Farquhar, Graham D. Unsaturation of vapour pressure inside leaves of two conifer species. United States. doi:10.1038/s41598-018-25838-2.
Cernusak, Lucas A., Ubierna, Nerea, Jenkins, Michael W., Garrity, Steven R., Rahn, Thom, Powers, Heath H., Hanson, David T., Sevanto, Sanna, Wong, Suan Chin, McDowell, Nate G., and Farquhar, Graham D. Wed . "Unsaturation of vapour pressure inside leaves of two conifer species". United States. doi:10.1038/s41598-018-25838-2. https://www.osti.gov/servlets/purl/1440441.
@article{osti_1440441,
title = {Unsaturation of vapour pressure inside leaves of two conifer species},
author = {Cernusak, Lucas A. and Ubierna, Nerea and Jenkins, Michael W. and Garrity, Steven R. and Rahn, Thom and Powers, Heath H. and Hanson, David T. and Sevanto, Sanna and Wong, Suan Chin and McDowell, Nate G. and Farquhar, Graham D.},
abstractNote = {Stomatal conductance (gs) impacts both photosynthesis and transpiration, and is therefore fundamental to the global carbon and water cycles, food production, and ecosystem services. Mathematical models provide the primary means of analysing this important leaf gas exchange parameter. A nearly universal assumption in such models is that the vapour pressure inside leaves (ei) remains saturated under all conditions. The validity of this assumption has not been well tested, because so far ei cannot be measured directly. Here, we test this assumption using a novel technique, based on coupled measurements of leaf gas exchange and the stable isotope compositions of CO2 and water vapour passing over the leaf. We applied this technique to mature individuals of two semiarid conifer species. In both species, ei routinely dropped below saturation when leaves were exposed to moderate to high air vapour pressure deficits. Typical values of relative humidity in the intercellular air spaces were as low 0.9 in Juniperus monosperma and 0.8 in Pinus edulis. These departures of ei from saturation caused significant biases in calculations of gs and the intercellular CO2 concentration. Thus, our results refute the longstanding assumption of saturated vapour pressure in plant leaves under all conditions.},
doi = {10.1038/s41598-018-25838-2},
journal = {Scientific Reports},
number = 1,
volume = 8,
place = {United States},
year = {2018},
month = {5}
}

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    Works referencing / citing this record:

    Equivalence of foliar water uptake and stomatal conductance?
    journal, November 2019

    • Binks, Oliver; Coughlin, Ingrid; Mencuccini, Maurizio
    • Plant, Cell & Environment, Vol. 43, Issue 2
    • DOI: 10.1111/pce.13663

    Equivalence of foliar water uptake and stomatal conductance?
    journal, November 2019

    • Binks, Oliver; Coughlin, Ingrid; Mencuccini, Maurizio
    • Plant, Cell & Environment, Vol. 43, Issue 2
    • DOI: 10.1111/pce.13663