Original Research

Comparative field performance of three different gas exchange systems

G. F. Midgley, M. Veste, D. J. don Willert, G. W. Davis, M. Steinberg, L. W. Powrie
Bothalia | Vol 27, No 1 | a662 | DOI: https://doi.org/10.4102/abc.v27i1.662 | © 1997 G. F. Midgley, M. Veste, D. J. don Willert, G. W. Davis, M. Steinberg, L. W. Powrie | This work is licensed under CC Attribution 4.0
Submitted: 07 October 1997 | Published: 07 October 1997

About the author(s)

G. F. Midgley, Stress Ecology Research Programme, National Botanical Institute, South Africa
M. Veste, Stress Ecology Research Programme, National Botanical Institute, South Africa
D. J. don Willert, Department of Applied Botany, University of Münster, Germany
G. W. Davis, Stress Ecology Research Programme, National Botanical Institute, South Africa
M. Steinberg, Department of Applied Botany, University of Münster, Germany
L. W. Powrie, Stress Ecology Research Programme, National Botanical Institute, South Africa

Full Text:

PDF (936KB)

See Updates


Share this article

Bookmark and Share

Abstract

We compared portable and continuously monitoring gas exchange systems under field conditions, using Protea glabra Thunb. as a test species. The aim was to determine if the same patterns of gas exchange and ancillary parameters could be obtained with rather different measurement systems, and whether the same interpretation and conclusions about environmental control of gas exchange could be drawn. The following systems were compared: 1, a ‘closed’ portable 1RGA manufactured by Ll-Cor (LI-6200); 2, an ‘open’ portable porometer manufactured by Walz; and 3, a continuously monitoring minicuvette system with temperature control facility, also manufactured by Walz.

All three systems yielded similar diurnal curves for CO2  uptake, although absolute flux values for the minicuvette system were lower than those obtained for the portable systems. This was likely due to stem respiration and self-shading of leaves on the shoot enclosed in the minicuvette. Differences in sampling technique between the two portable systems, primarily with regard to changes in leaf orientation, resulted in some differences in absolute values of gas fluxes and ancillary parameters such as leaf temperature and leaf to air vapour pressure difference. However, data from all three systems allowed similar interpretations to be made about the environmental dependencies of gas exchange patterns. It appears that each system has certain drawbacks associated with widely varying field conditions. A combination of portable and continuous monitoring techniques would seem to be the most powerful approach to investigating the gas exchange patterns of terrestrial plants in their natural environment.


Keywords

ecophysiology; gas exchange measurement; photosynthesis; transpiration

Metrics

Total abstract views: 1094
Total article views: 2014


Crossref Citations

No related citations found.