Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leaf‐mediated pores

Kristine Stove Boesgaard, Teis Nørgaard Mikkelsen, Helge Ro‐Poulsen, Andreas Ibrom

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

There is an ongoing debate on how to correct leaf gas exchange measurements for the unavoidable diffusion leakage that occurs when measurements are done in non‐ambient CO2 concentrations. In this study, we present a theory on how the CO2 diffusion gradient over the gasket is affected by leaf‐mediated pores (LMP) and how LMP reduce diffusive exchange across the gaskets. Recent discussions have so far neglected the processes in the quasi‐laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer at the exterior of the cuvette is enriched with air from the inside of the cuvette. The effect can thus be reduced by reducing the boundary layer thickness. The theory clarifies conflicting results from earlier studies. We developed leaf adaptor frames that eliminate LMP during measurements on delicate plant material such as grass leaves with circular cross section, and the effectiveness is shown with respiration measurements on a harp of Deschampsia flexuosa leaves. We conclude that the best solution for measurements with portable photosynthesis systems is to avoid LMP rather than trying to correct for the effects.
Original languageEnglish
JournalPlant, Cell and Environment
Volume36
Issue number7
Pages (from-to)1352-1362
ISSN0140-7791
DOIs
Publication statusPublished - 2013

Keywords

  • CLIMAITE project
  • CO2 leakage
  • Diffusion leakage
  • Gasket density
  • Laf adaptor frame (LAF)
  • Leaf respiration
  • Portable gas exchange system

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