1. High-Speed CO2 Ramping TECHNIQUE
Interested in performing rapid A/Ci curves in less than 5 minutes? Not only is it possible it is fast and easy with the CIRAS-3 Portable Photosynthesis System

2. Why A vs. Ci curves?
Single point leaf gas exchange measurements tell you what is currently occurring, but do not reveal much about the underlying physiological traits.
A/Ci curves also reveal (for C3 species):
VCmax, J, and sometimes TPU
Rd, gm
Allow predictions of A under a range of conditions

3. Steady State A /Ci Curve (Sunflower)

4. A vs. Ci Curve Analyzed by Sharkey et al. Utility

5. Steady-State A vs. Ci Curves, Continued
Parameters derived:
VCmax = 253 (µmol m-2 s-1)
J = (µmol m-2 s-1)
TPU = (µmol m-2 s-1)
Rd = (µmol m-2 s-1)
gm = (µmol m-2 s-1 Pa-1)

6. Faster A/Ci Curves High Speed CO2 Ramping

7. High-Speed CO2 Ramping Technique
Step 1- Perform a “store differential balance” for the CO2 and H2O range to be covered.
Step 2 - Perform a CO2 ramp with an empty cuvette.
Step 3 - Perform a CO2 ramp with a leaf in the cuvette and continue to perform multiple ramps with different leaves.
Step 4 - Post-process the data.

8. CO2 Ramp with Empty Cuvette and with Leaf in the Cuvette
Our light unit is normally used to control light intensity in the chamber but it is not shown here.

9. Post-Processing Data

10. A/Ci Curve High-Speed CO2 Ramp

11. Advantages
Small system volume means rapid equilibration and measurement of photosynthesis at each level.
Multiple points on A vs. Ci curves for analysis.
Total time of 5 minutes per leaf is possible for complete curves.
Stomatal conductance changes very little.
Customizable scripts suitable for both C3 and C4 species- different biochemical parameters are obtained.

12. Thank You PP Systems 110 Haverhill Road Suite 301 Amesbury, MA USA Tel: