Product Information

AP4 porometer

The stomatal aperture is the dominant factor in the diffusion conductance of leaf surfaces; this regulates both the loss of water from leaves and the absorption of CO2 for photosynthesis. The measurement of diffusion conductance is therefore an important indicator for the plant water balance and provides a valuable insight into plant growth and adaptation of the plant to the respective environmental conditions.
The AP4 measures the diffusion conductance by comparing the precise rate of humidification within a small cuvette to readings obtained on a calibration plate. This plate has 6 settings for diffusion conductance whose values have been accurately determined using finite element analysis.
The information cited on the accuracy of other porometers and gas analysis systems is based on time-consuming laboratory arrangements and calibration procedures which bear little comparison to operating conditions in the field. By contrast the AP4 features simple, direct calibration in the field in line with a tested physical standard. The special leaf chamber minimises leaf stress and therefore unwanted stomatal closure. The light and ergonomic sensor head, the large and clear LCD display and complete QUERTY keyboard also ensure that it is extremely user-friendly.



  • Direct readout of stomatal conductance or resistance
  • Simple calibration in the fied
  • Minimisation of leaf stress during measurement
  • Award-winning user interface




Technical Specifications

Technical Specifications

Conductance measurement range:5 … 1200 mmol/m2s
Conductance measurement range:0,25 … 30 mm/s
Resistance measurement range:0,2 … 40 s/cm
RH measurement range:0 … 100 %
Temperature measurement range in
measurement chamber:
-5 … 55 °C
Leaf temperature measurement range:5 … 5 °C
PAR measurement range:0 … 2500 μmol/m2s
Pressure measurement range:600 … 1200 hPa



Order Numbers + Accessories


Ordering Details:

Art.-Nr.:  176120 AP4 prorometer




Tel.: +49 (0) 33432 - 89 575
Fax: +49 (0) 33432 - 89 573

Niederlassung Süd
Tel.: +49 (0) 8161 - 23 46 441
Fax: +49 (0) 8161 - 23 46 443