Delta-T Devices Ltd. AP4 Sheet Porometer

Direct measurement of stomatal conductance or resistance
Simple absolute calibration in the field
Minimum sheet stress during measurement
Ideal for phenotypic studies
Award-winning user interface design
5 year warranty

Stomatal opening is a key determinant of the diffusive conductance of leaf surfaces, which controls both water loss from plant leaves and CO2 uptake for photosynthesis. Measurements of diffusive conductance are important indicators of plant water status and provide valuable insights into plant growth and adaptation to environmental variables.

AP4 Leaf Porometer Features

The AP4 Leaf Porometer measures diffusion conductivity by comparing the exact wetting rate in a small cavern (chamber) with readings obtained from a calibration plate. The plate has 6 diffusion conductivity settings, the values of which have been precisely determined by finite element analysis.

Other accuracy metrics for porometers and gas analysis systems rely on lengthy laboratory setups and calibrations that are poorly suited to field conditions. In contrast, the AP4 Leaf Porometer features simple, direct field calibration against a verified physical standard.

The AP4 Leaf Porometer has many other features designed to ensure that accurate, repeatable measurements are made as easily as possible:

Sophisticated temperature compensation
Insoluble leaf chamber minimally inhibits unwanted stomatal closure
Lightweight and ergonomic sensor heads
Large clear LCD display (8 lines of 40 characters)
Full QWERTY keyboard for annotations on up to 1500 measurements
A robust and reliable tool for phenotypic projects
More than 2000 Delta-T porometers are in use worldwide

Porometer design collaboration with Prof. John Monteith

Delta-T Devices has worked closely with Professor John L. Monteith (1929–2012) for forty years – from the production of the world's first automatic porometer in the 1970s, through several subsequent versions – to the modern AP4 Porometer.

Delta-T Devices founder Ed Potter shared the stage with several speakers to pay tribute to Professor John L. Monteith at the 2013 American Society of Agronomy Annual Conference in Tampa, Florida. The talk presented the history of the development of the automated porometer.

Dynamic diffusion porometers, such as AP4, are also known as stomatal diffusion porometers.