What's what

The LI-6800 measures leaf-level gas exchange with three chambers: the 6800-01/A fluorometer, the 6800-12/A small leaf chamber, and the 6800-13 large leaf chamber. Here we describe how to use these chambers for leaf-level gas exchange measurements, as well as the small plant chamber, large leaf chamber, sprig adapter kit, bryophyte chamber, insect chamber, and custom adapter kit. Each chamber uses a flow path similar to that shown in An open gas exchange system.

Both the small and large leaf chambers, when not equipped with a light source, have a clear Propafilm™ top that can be used under ambient light. Both also can be outfitted with a light source. The light source on the 6800-01A fluorometer is permanently attached and cannot be removed. It can be operated as a fluorometer or standard light source. All leaf chambers feature one or more leaf temperature thermocouples that make contact with the bottom of a leaf to measure its temperature during measurements and a photodiode that measures light in the chamber.

Fluorometer chamber

The 6800-01A fluorometer is a combined chamber and light source that induces and measures fluorescence from a leaf or an aquatic sample with the aquatic chamber. In the leaf configuration, it includes aperture inserts to limit the opening to 6 cm2 or 2 cm2. See Measuring chlorophyll a fluorescence for installation instructions and a list of components.

Figure 9‑9. The fluorometer chamber is used for leaf-level gas exchange measurements.

Small leaf chamber and light source

The small chamber features a transparent Propafilm™ top window. It accommodates one fine wire thermocouple to measure leaf temperature. A GaAsP light sensor measures PAR in the chamber. It is compatible with the 3×3 cm light source. Aperture inserts limit the opening to 3×3 cm, 2×3 cm, or 1×3 cm. See Installing the small leaf chamber for details. The chamber includes the following items:

Description Quantity Part Number
Chamber 1 9968-264
1×3 cm Aperture Inserts 2 9968-294
2×3 cm Aperture Inserts 2 9968-295
3×3 cm Aperture Inserts 2 9968-296
Spares Kit 1 9968-269
O-ring; 6×1.5 mm 1 192-14314
O-ring; 48×1.5 mm; for Apertures 2 192-16680
Light Source Gaskets1 3 6568-071
3×3 cm Aperture AP Gaskets (white upper/lower) 2 6568-511
2×3 cm Aperture AP Gaskets (white upper/lower) 2 6568-562
1×3 cm Aperture AP Gaskets (white upper/lower) 2 6568-560
3×3 cm Aperture PE Gasket (white upper) 4 6568-429
3×3 cm Aperture NP Gasket (black lower) 4 6568-384
2×3 cm Aperture PE Gasket (white upper) 4 6564-156
2×3 cm Aperture NP Gasket (black lower) 4 6564-028
1×3 cm Aperture PE Gasket (white upper) 4 6568-584
1×3 cm Aperture NP Gasket (black upper) 4 6568-583
Figure 9‑10. The small leaf chamber (left) with light source (right).
Figure 9‑11. Typical spectral output of the LEDs in the 3×3 cm light source.

Large leaf chamber and light source

The 6×6 cm chamber features a clear Propafilm™ top window. It holds two fine wire thermocouples to measure the leaf temperature. An internal, upward facing GaAsP light sensor measures PAR in the chamber. It is compatible with the 6×6 cm light source. See Installing the large leaf chamber for details. The chamber includes the following items:

Description Quantity Part Number
Chamber 1 9968-159
Large Light Source Adapter Plate 1 9968-209
Large Light Source Chamber Adapter Kit 1 9968-189
Adapter Plate 2 9868-209
Mounting Screws; M3×0.5 8 mm 4 150-07475
Bottom Chamber Light Source Adapter Kit 1 9968-311
Light Source Spacer 1 9868-245
Screws; M3×0.5 10 mm 4 150-15307
Spares Kit 1 9968-207
O-ring; 6×1.5 mm 1 192-14314
O-ring; AS-154 Viton 75 1 192-12205
6×6 cm AP2 Gasket (white upper/lower) 2 6568-513
6×6 cm NP Gasket (black lower) 3 6568-210
6×6 cm PE Gasket (white upper) 6 6568-463
Thermocouple Hole Plug 2 6568-523
Propafilm Kit 1 9964-151
Figure 9‑12. Large leaf chamber (left) with light source (right).
Figure 9‑13. Typical spectral output of the blue, green, red, and white LEDs in the 6×6 cm large light source.