CO2 Response Curves

CO2 response curves indicate plant responses to CO2 concentrations, which provides information on the biochemical limitations to photosynthesis. These data can be used to assess Amax (maximum photosynthesis rate), VCmax (maximum rate of Rubisco carboxylation), Jmax (maximum rate of electron transport for RuBP regeneration) triose phosphate utilization (TPU) limitations and other parameters. Click here for more information on how the LI-6400XT controls CO2.

CO2 response graph

Photosynthetic response to increasing CO2. Glycine max (soybean) leaf was excised from experimental-garden grown plant and then light acclimated at 1500 µmol m-2 s-1 (saturating) in a lab. Experimental data (circles) were modeled using the equations of Farquhar, von Caemmerer and Berry (1980) for maximum velocity of carboxlation (VCmax, black line) and the maximum electron transport rate for RuBP regeneration (Jmax, cyan line). The intercellular CO2 (Ci) at which photosynthesis transitions from VC-limited to J-limited is 216 μmol CO2 mol-1 air. Stomatal limitation to photosynthesis (l ) is the effect of the stomatal resistance restricting photosynthesis decreasing CO2 available for photosynthesis at growth CO2 concentration.

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