Porometer/ Fluorometer

For broadleaves

The LI-600 is the only handheld instrument that measures both stomatal conductance and chlorophyll fluorescence over the same leaf area.

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Leaf sizes

Length and width: minimum 7.5 mm

Thickness: maximum 2.8 mm

Diagram showing the features of the LI-600PF Porometer/Fluorometer. Diagram showing the features of the LI-600PF Porometer/Fluorometer.

How it's different

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.

How it works

The LI-600 brings together numerous innovative technologies to deliver fast, accurate, and dependable measurements in a compact, handheld device.

Stomatal conductance

The 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
Map with LI-600 GPS data points and text.
LI-600 data set
Figure 1. Three time series of measurements taken at different times of day on three adjacent leaves of three plants. The series are overlaid to show that the instrument can complete measurements in 6 to 9 seconds at a range of gsw values. Data points when not clamped between leaves not shown for clarity. Measurements are one-side stomatal conductance (gsw) made on three adjacent leaves (orange is soy shortly after sunrise; gsw = 0.055, blue is soy near midday; gsw = 0.17, and green is tobacco at midday; gsw = 0.51). Data are the 2 Hz measurements from the LI-600.

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