Porometer/ Fluorometer

For needles, narrow leaves, and grasses

The LI-600N Porometer/ Fluorometer is the only instrument specifically optimized to measure the stomatal conductance and chlorophyll fluorescence of a single needle, narrow leaf, or blade of grass.

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Leaf sizes

Width: 1-3.5 mm

Length: minimum 14.2 mm

Thickness: maximum 2.8 mm

Diagram showing the features of the LI-600N Porometer/Fluorometer Diagram showing the features of the LI-600N Porometer/Fluorometer

How it's different

The LI-600N is designed to quickly survey needles, narrow leaves, and grasses under ambient conditions.

  • Reaches stability in 5-15 seconds across a range of gsw rates.
  • Utilizes user-configurable stability criteria.
  • Log a measurement with the press of a button.

How it works

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

Stomatal conductance

The LI-600N uses an open flow-through differential measurement for quantifying transpiration (E) and stomatal conductance around the needle or narrow 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-600N 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
Diagram of how the LI-600N works.

High accuracy at low conductance

Get high-quality, accurate measurements from single needles and blades of grass, even at extremely low conductance.

Loblolly low gsw graph
Figure 1. Survey measurements of well-watered (WW) or water-stressed (WS) single loblolly pine (Pinus taeda) needles. Each point is the mean (±SE) of four measurements on four different greenhouse-grown seedlings measured at growth irradiances of 150-200 µmol m-2 s-1 PPFD.
Pinus mugo needles graph
Figure 2. Autumn diurnal measurements of stomatal conductance (gsw) and quantum yield of PSII (PhiPS2) of Pinus mugo needles measured on a clear day using the LI-600N. The points are the means of 3 needles (±SE) on the same plant. Each measurement period was about a minute to collect the data.
Single GH Buffalo grass MPF
Figure 3. A high-quality Multiphase Flash™ (MPF) measurement on a single blade of greenhouse-grown buffalograss (Bouteloua dactyloides) at ambient PPFD of 670 µmol m-2 s-1.

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