John Morris

• Field-portable conifer photosynthesis measurements with up to full-sun light intensity
• Enables light and CO2 response studies for conifer species
• Accommodates conifer sprigs up to 7.5cm long with needles up to 3.5cm

The 6400-22 Opaque Conifer Chamber is the newest addition to the family of leaf chambers and accessories available for the LI-6400/LI-6400XT Portable Photosynthesis System. The 6400-22L Lighted Conifer Chamber Package combines the 6400-22 Opaque Conifer Chamber (Figure 1) and the 6400-18 RGB Light Source, which are also available separately. The 6400-22 is constructed with an opaque plastic material that has excellent resistance to water sorption. It is designed to mate with the 6400-18 RGB Light Source so that users can make response curve measurements on short-needle conifers in the field.


Figure 1. The Opaque Conifer Chamber mounted on the IRGA. The RGB Light Source mounts atop the Opaque Conifer Chamber.

The 6400-22 measures conifer sprigs up to 7.5cm long, with needles up to 3.5cm long. The interior reflects light from the RGB Light Source back onto the underside of the conifer sprig. An external quantum sensor mounted to a chamber support bracket measures ambient light levels. A thermocouple suspended in the air exhaust port measures the temperature of air exiting the chamber, which is used to compute leaf temperature with an energy balance equation.

With the 6400-22L Lighted Conifer Chamber Package (Figure 2), CO2 and light response curves can be generated automatically using an AutoProgram.


Figure 2. The 6400-22L consists of the 6400-22 Opaque Conifer Chamber, and the 6400-18 RGB Light Source.

The 6400-18 (Figure 3) is a 7cm diameter LED light source with three independent wavelengths (Red, Green, and Blue - RGB) that can be combined in any proportion, including white light (equal quanta of red, green, and blue). Temperature and humidity can also be controlled inside the chamber.


Figure 3. The 6400-18 RGB Light Source provides any proportion of red, green, blue, or white light (equal parts RGB).

Powering the 6400-18 RGB Light Source
The 6400-18 is powered separately from the LI-6400/LI-6400XT; an AC Power Supply and a DC Adapter (p/n 9964-126) are included (Figure 4). The DC Adapter has bare wire leads for connecting to a user-supplied battery.


Figure 4. An AC power supply and DC adapter (not shown) are included with the 6400-18 RGB Light Source.

An optional 6400-28 Battery Belt Kit (Figure 5) is available to power the 6400-18 in the field. The Battery Belt Kit contains a charger, a waist/shoulder pack that holds a single rechargeable NiMH battery, and a hot swap box for connecting a second battery without power interruption. One battery will power the RGB Light Source for 2-5 hours, depending on desired light intensities. Extra batteries are available under part number 9964-122. The batteries require about 6 hours to recharge; only one battery can be recharged per charger. Extra battery chargers are available as well, under part number 9964-138.


Figure 5. The optional 6400-28 Battery Belt Kit is available to power the 6400-18 in the field.

Instrument Software Compatibility
The 6400-18 RGB Light Source and 6400-22 Opaque Conifer Chamber both require LI-6400/6400XT OPEN 6.1 software or above. Instruments running OPEN 5.x and above can upgrade to OPEN 6.1 software for free. Older instruments will require a digital board upgrade to run OPEN 6.1. Contact us for upgrade details.