Measuring Photosynthesis and Respiration in Turfgrass
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
Dale J. Bremer and Jay M. Ham. 2005. Measurement and Partitioning of In situ CO2 Fluxes in Turfgrasses Using a Pressurized Chamber. Agronomy Journal 97:627-632 [errata: 98:1375]. (Request reprint).
Posters:
Photosynthesis and Respiration Measurements in Turfgrass with a Custom Surface Chamber. Dale J. Bremer, Jason D. Lewis, and Jay M. Ham. Presented at the ASA-CSSA-SSSJ meetings in Houston, TX, Oct 5-9, 2008.
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.
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.
