Byrophyte Chamber

Printable PDF: 6400-24 Bryophyte Chamber installation and operational instructions

Instructions for installing the 6400-24 Bryophyte Chamber onto the LI-6400/XT Portable Photosynthesis System.

The 6400-24 Bryophyte Chamber has a clear aperture for a user-supplied light source (i.e., natural sunlight, growth cabinet, etc.), or the 6400-18/A RGB Light Source can be attached.

NOTE: If you are measuring very moist samples, conden- sation can form in the exhaust tube if the chamber tem- perature rises above ambient temperature. If that happens, matching will introduce serious errors, since the air’s water vapor concentration will change as it transits to the Reference cell. To prevent this problem: 1) run the coolers to keep the chamber temperature below ambient, or 2) consider changing the match method to fan-based (with Fan turned Off). See the instruction manual for more details.

The assembly requires a Phillips head screwdriver and the included 3/32” hex key, and takes about 15 minutes to complete.

Follow these steps to install the 6400-24:

Remove the Standard Chamber

  1. The 6400-24 replaces the lower half of the standard leaf chamber. Remove the tripod mounting plate, if necessary, and disconnect the internal PAR sensor connector on the side of the sensor head by gently pulling straight out (Figure 1‑1).
  2. Use the 3/32” hex key to loosen the two long screws, and remove the top half of the standard leaf chamber (Figure 1‑2). Disconnect the purple leaf temperature thermocouple by pulling straight out (Figure 1‑1). Loosen the two screws on the lower half of the stan- dard leaf chamber, and disconnect the lower chamber exhaust tube.
Figure 1‑1. Disconnect the PAR sensor on the side of the sensor head.
Figure 1‑2. Remove the top half of the standard leaf chamber with the 3/32” hex key.

Install the 6400-24 Chamber

  1. Cut a piece of Propafilm® from the supplied roll approximately 3 cm x 8 cm. With the sensor head open, position the Propafilm over the black spacer on the lower leaf chamber manifold (Figure 1‑3). Close the sensor head to secure the Propafilm in place. This will divert air flow away from the unused top half of the leaf chamber. Pull lightly on the Propafilm; if it moves, open the sensor head, tighten the knurled nut on the chamber tension adjustment assembly (Figure 1‑1), and repeat.
  2. Figure 1‑3. Place the strip of Propafilm over the 3 holes on the black spacer on the lower leaf chamber manifold and then close the sensor head tightly to hold the Propafilm in place.
  3. Install two small and one large o-rings on the air passage holes on the back edge of the 6400-24 (Figure 1‑4). Use the 3/32” hex key and four hex head screws to install the chamber to the lower leaf chamber manifold (Figure 1‑5).
  4. Figure 1‑4. Install two small and one large o-rings on the air passage holes on the back side of the chamber.
    Figure 1‑5. Attach the chamber to the lower leaf chamber manifold using four 1/2” hex screws as shown above.
  5. The 6400-24 uses a reversible bottom plate; one side has a shallow well, and the other side has a raised screen. There are 4 Phillips head screws that attach the bottom plate to the 6400-24. Note, too, that there is a large o-ring that fits in a groove on the underside of the chamber; make sure the o-ring is in place when attaching the bottom plate.
  6. Connect the chamber air temperature thermocouple by pushing the purple connector into the connector on the sensor head. Install the standard exhaust tube onto the metal tube on the underside of the sensor head, and then onto the metal tube on the bottom of the 6400-24.
  7. Figure 1‑6. Install the lower plate in either orientation using the 4 Phillips head screws included.
    Figure 1‑7. Install the standard exhaust tube onto the metal tubes shown.
    Figure 1‑8. Finished assembly.

Configure the Software

  1. The 6400-24 requires OPEN version 6.2 or above. OPEN 6.2 can be installed on 200 MHz (previous version OPEN 5.x) or 400 MHz (previous version OPEN 6.x) digital boards. Older boards require a digital board upgrade. Contact LI-COR for more details. Note that OPEN version 6.1 does not support the 6400-24 directly; however, you can choose the 6400-17 Whole Plant Arabidopsis Chamber when creating a new configuration as described below, which will work with the 6400-24.
  2. To finish the installation, choose the Config Menu (f2) from OPEN’s main screen, and follow the steps below. See LI-6400/LI-6400XT Instruction Manual, Section 8, Light Sources and Sensors, for more information.
    1. Choose New from the Config Menu.
    2. Scroll down to Larger Chambers.
    3. Choose the 6400-24 Bryophyte Chamber.
    4. Select an external quantum sensor.
    5. The Bryophyte Install dialog:
    6. (Sample) Material: “Broadleaves”,“Needles”, or “Mass-based”.
    7. Computations: “Photo, Trans, Cond, Ci” or “Photo, Trans only”.
    8. For leaves and needles, the normal set of gas exchange computations will be done. For mass- based material, the computations automatically will be “Photo, Trans only”, which means only photosynthesis (μmol/kg/s) and transpiration (mmol/kg/s) are computed.
    9. After you have configured the settings, press f5 (DoIt), and then press N.


  1. Alternatively, you can make a new configuration for a Light Source (e.g. the 6400-18/A RGB Source), and then select the 6400-24 as the underlying chamber. Note that there is no difference between configurations for the 6400- 17 Whole Plant Arabidopsis Chamber and the 6400-24 Bryophyte Chamber when created in OPEN v6.2, other than the default configuration name.
  2. In New Measurements mode, the level 3 fct keys look slightly different with a mass-based configuration: f1 will prompt for mass (in grams) instead of leaf area, and there is no stomatal ratio key (f2).


Area-based (leaves and needles):