LI-COR LI-600 and LI-600N Porometer / Fluorometers

The LI-600 and LI-600N are compact porometers with Pulse-Amplitude Modulation (PAM) fluorometers that simultaneously measure stomatal conductance and chlorophyll a fluorescence over the same leaf or needle area. A GPS receiver tracks location and an accelerometer/magnetometer records data needed to calculate a leaf’s angle of incidence to the sun. Capable of completing these measurements in seconds, the LI-600 and the LI-600N deliver speed and precision.

Time-saving features for fast surveys

• Simple, intuitive display shows instrument status and most recent measurement.
• Ergonomic, lightweight design allows for easy single-handed operation.
• GPS receiver records measurement location.
• Barcode generator in the desktop software creates custom barcode labels.
• Barcode scanner records sample information and reduces manual data entry errors.
• Optional user-defined prompts in the measurement workflow help keep data organized.
• Built-in rechargeable battery powers 8 hours or more of active use.

Why measure stomatal conductance and chlorophyll a fluorescence?

Combined measurements of stomatal conductance and chlorophyll a fluorescence present a more complete picture of a plant’s physiological state than either technique alone.

Stomatal Conductance

Stomatal openings regulate the exchange of water vapor and CO₂ between a leaf and the air. Stomatal conductance to water (g_sw), which responds to light, CO₂, temperature, and humidity, among others, is a measure of the degree of stomatal openness and the number of stomata. It is an indicator of a plant’s genetic makeup and physiological response to environmental conditions.

Measurements of chlorophyll a fluorescence can provide information about the leaf’s quantum efficiency, electron transport rate (ETR), non-photochemical quenching (NPQ), as well as an assortment of reactions that collectively protect a leaf when it absorbs excessive light energy.

Understanding these processes is important to many research applications, including genetic screening, agronomy, plant physiology, ecology, climate change research, and stress tolerance.

Chlorophyll a fluorescence

Measurements of chlorophyll a fluorescence provide insights into photosynthesis, and, when combined with stomatal conductance, results in a more complete picture of the overall plant physiology and health. In addition to rectangular flashes, the LI-600 and LI-600N support multiphase flashes (MPF), which can prevent underestimation of F_m‘ (Loriaux et al., 2013) and thereby reduce bias in numerous fluorescence parameters.

Loriaux SD, et al. (2013). Closing in on maximum yield of chlorophyll fluorescence using a single multiphase flash of sub-saturating intensity. Plant Cell Environ 36:1755-1770.

Light-adapted leaves

For light-adapted leaves, the LI-600 and LI-600N measure the quantum yield of fluorescence (Φ_PSII), or the proportion of light absorbed by PS_II used in biochemistry.

F_m‘ is maximum fluorescence yield in a light-adapted leaf; F_s is steady-state fluorescence yield in a light-adapted leaf.

Dark-adapted leaves

For dark-adapted leaves, the LI-600 measures maximum quantum yield (F_v/F_m), or the maximum proportion of absorbed light that can be used to drive photochemistry.

F_v is variable fluorescence yield in a dark-adapted leaf; F_m is maximum fluorescence yield in dark-adapted leaf; F_o is minimum fluorescence yield in a dark-adapted leaf.

Leaf angle measurements

The angle of incidence of a leaf– its orientation to the sun at a given time and place–is a useful variable for understanding a plant’s architecture and its physiological responses to the environment. A leaf’s angle of incidence may change, for example, to maximize light intensity for photosynthesis, minimize light intensity to conserve water, or allow light through a canopy to lower leaves. Knowing the angle of incidence of a leaf can lead to insights into how light intensity drives photosynthesis, and into the differences in measurements taken on the same plant.

The accelerometer/magnetometer measures three variables–heading, pitch, and roll–and the GPS receiver records leaf location and solar position. The LI-600/LI-600N software uses these data to calculate the angle of incidence for each leaf measurement, allowing researchers to evaluate a plant’s environmental status more thoroughly.

Stomatal conductance (g_sw) measured with a GPS-enabled LI-600. Georeferenced measurements from the LI-600 are easily viewed in mapping applications including Google Earth™ and Esri^® ArcGIS^®.

GPS

The LI-600 records your position using GPS data when a measurement is taken, giving you the ability to track locations and return to specific areas over time. The LI-600 records the date, time, latitude, longitude, and altitude of each measurement, and works with the accelerometer/ magnetometer to record the data needed to calculate a leaf’s angle of incidence.

Software that simplifies your work

You can configure the LI-600 and LI-600N with ease – just set a few parameters in the computer software and you are ready to collect data. Each LI-600/LI-600N can store up to four configurations, making it easy to switch from one protocol to another. You can save numerous configurations on your Mac or PC and share configuration files with colleagues. Configurations are easily loaded from the software onto the device through a USB connection.

Whether you are preparing for measurements, evaluating data files, or verifying the calibration, the computer software presents a simple, intuitive interface that lets you focus on the task at hand.

LI-COR LI-600 and LI-600N Porometer / Fluorometers – Sigmatech Inc. Philippines