Field
measurements of photosynthesis in turfgrass are often conducted with surface
chambers that cover a small area of the canopy. Consequently, measurements
include the various components of ecosystem carbon (C) balance, including photosynthesis,
canopy respiration and soil respiration. When used for measuring carbon flux,
steady-state portable photosynthesis systems (i.e., Licor 6400) are pressurized.
Small changes in pressurization are known to partially suppress soil respiration.
Thus, chamber measurements of CO2 flux from turf may be more related to unintended
changes in soil respiration than to changes in photosynthesis. Furthermore,
because chambers are small, single measurements may not be representative of
overall canopy photosynthesis where spatial variability is high (e.g., in green
leaf area index, soil moisture). Finally, measurements with many portable photosynthesis
systems may take up to four minutes, during which time the conditions that
affect photosynthesis (e.g., air temperature) may change significantly inside
the chamber. At Kansas State University, we are investigating these issues
and others to develop new techniques and chambers that improve accuracy in
measurements of photosynthesis and respiration, which are crucial components
of basic research in turfgrass science.
Publications:
Peer-reviewed
Measurement and Partitioning
of In situ CO2 Fluxes in Turfgrasses Using a Pressurized Chamber. 2005. Dale J. Bremer and Jay M. Ham.
Agronomy Journal 97:627-632 [errata:
98:1375].
Posters:
Measurement and Partitioning of in situ Carbon Fluxes in Turfgrasses. Dale J. Bremer, Jay M. Ham, and K. Su. Presented at the ASA-CSSA-SSSJ meetings in Denver, CO, Nov 2-6, 2003.
Measurement of Photosynthesis and Respiration in Turfgrass with Large and Small Surface Chambers. Dale J. Bremer, Jason D. Lewis, Jamey L. Duesterhaus, and Jay M. Ham. Presented at the ASA-CSSA-SSSJ meetings in New Orleans, LA, Nov 4-8, 2007.
