Fig. 2

An Arabidopsis dynamic flow cuvette for gas exchange measurements and ¹³CO₂ labeling assays. A Top view showing directional air flow (red arrow). B The cuvette with Arabidopsis plant installed. A ball valve at the exit can vent directly to the atmosphere during liquid nitrogen freezing to protect downstream gas sensors. C Close up showing lid-embedded fan, deflector, and thermocouple. D Arrangement of leaves around lid components. E Thermocouple placement against abaxial leaf surface in sealed cuvette. F Gas exchange and labeling assays of a pair of Arabidopsis plants in identical cuvettes using a common light source. G Gas manifold for tandem labeling cuvettes. A mounted ball valve rapidly switches the gas supply to the cuvette from standard air to ¹³CO₂-containing air to initiate a labeling experiment. Digital flow controllers maintain constant flow to each cuvette independently. Gas supply to the cuvettes can be configured for tandem or independent operation. H A pressurized wash bottle with safety vent adjusts humidity upstream of the gas switching valve. I Temperature inside the cuvette is regulated by a series of internal irrigation channels (Fig. 1A) connected to a circulating water bath (not shown). The cuvettes can be linked together as shown to ensure equal temperatures between two experimental plants. J Machined camming screw hole for sealing the lid. K Lid in loose, open position for rapid removal and liquid nitrogen introduction during flash freezing. L Lid locked in sealed position