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LI-COR - Model LI-600 -Handheld Porometer/ Fluorometer
The LI-600 is the only handheld instrument that measures both stomatal conductance and chlorophyll fluorescence over the same leaf area.

The LI-600 is designed to quickly survey broadleaves under ambient conditions.
- Reaches stability in 5-10 seconds across a range of gsw rates.
- Utilizes user-configurable stability criteria.
- Performs automatic logging to record a measurement when stable.
The LI-600 brings together numerous innovative technologies to deliver fast, accurate, and dependable measurements in a compact, handheld device.
Stomatal conductanceThe LI-600 uses an open flow-through differential measurement for quantifying transpiration (E) and stomatal conductance on one side of the leaf. First, E is quantified by measuring the flow rate and water vapor mole fraction of air that enters and leaves the chamber. Meanwhile, total conductance to water vapor (gtw) is computed as a function of E and vapor pressure in the leaf and cuvette. Finally, stomatal conductance to water (gsw) is computed as a function of gtw and the boundary layer conductance to water vapor (gbw).
The advantages of the LI-600 measurement flow path include the following:
- Flow rates quickly flush through the small chamber volume and result in rapid stabilization for quick measurements
- A differential measurement in close to ambient conditions
- Minimally disturbed light, CO2, and H2O during the measurement eliminate the need for desiccant chambers or corrections for large diffusion gradients
- Automatic matching accounts for drift between the reference and sample sensors
