Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables

Kevin A. Simonin, Adam B. Roddy, Percy Link, Randy Apodaca, Kevin P. Tu, Jia Hu, Todd E. Dawson, Margaret M. Barbour

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

During daylight hours, the isotope composition of leaf water generally approximates steady-state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady-state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of 18O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non-steady state. We show that non-steady-state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents.

Original languageEnglish (US)
Pages (from-to)2190-2206
Number of pages17
JournalPlant, Cell and Environment
Volume36
Issue number12
DOIs
StatePublished - Dec 1 2013
Externally publishedYes

Keywords

  • Stable water isotopes
  • Steady state
  • Transpiration

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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