PMR-5: For accurate measurement of leaf stomatal conductance

PMR-5 Steady State Porometer

A steady-state, continuous flow porometer described by Dr. K.J. Parkinson (1985) for the study of plant water relations in the field and laboratory. The main console is based on the EGM-4 Environmental Gas Monitor which supplies power (internal rechargeable 12V battery) and required interface for measurement of all sensor outputs from the cuvette for display, calculation and storage of porometry results.

Field shot of PMR-5 Steady State Porometer

The PMR-5 is a hand-held unit using an "open system" measurement of leaf transpiration. There is an integral mass-flow controlled air supply and manual control of humidity up to ambient. The lightweight cuvette is designed to couple the leaf to the ambient temperature using a fan, heat sink and radiation shield. There is a stirring fan in the chamber to minimize the boundary layer resistance. Digital humidity and temperature sensors accurately monitor the air entering and leaving the cuvette. These are closely situated in the chamber with tortuous air paths to minimize the temperature difference between sensors. A sensor matching process eliminates errors due to sensor imbalance.

There is continuous calculation and display of the reference and chamber humidity, leaf temperature (energy balance), airflow rate, incident PAR (Photosynthetically Active Radiation) and stomatal conductance. The transpiration rate is also recorded. The PMR-5 is a simple retrofit for existing EGM-4 customers. Please contact PP Systems for details.

The photo below shows a close up of the hand-held leaf cuvette.

PMR-5 Data Sheet

PMR Publications