PM-48MB Photosynthesis MonitoR
Multi-channel automated system for monitoring CO2 exchange of leaves

Back to all Phytech's Products



Contact Us


Unlike most of commercially available photosynthesis systems, the PM-48MB Photosynthesis Monitor is specially designed for long-term monitoring of CO2-exchange in several leaves simultaneously.  It is an open system with original leaf chambers. Due to self-clamping design, the LC-4A leaf chambers do not disrupt the natural conditions of the leaves under study.  The LC-4A chamber fixes exposed leaf and keeps it open between measurement cycles. The system operates with several chambers in such a manner that they are sequentially closed for a few minutes and then stay opened until the next measuring cycle starts.

Thus, the duration of measurement is basically limited only by the natural aging of the leaf under study, since the problem of leaf chamber effect is largely resolved due to the LC-4As self-clamping design.

Data is collected in the datalogger's memory and can be transferred to PC for further processing.



     Automatic long-term monitoring for several leaves   simultaneously

    Easy installation and operation

    Complete instrument for greenhouses and laboratories



LC-4A leaf chambers on tomato plants in a greenhouse

A lower chamber is currently active, three others are staying in queue



System Overview

A chamber is mounted on a stand. Two special clips, attached to the chamber, secure a leave under study. This feature is critically important because it ensures the diurnal records to be consistent.
Each leaf chamber has a reference CO2 channel.   The automatic self-clamping design enables keeping a leaf open for more than 90% of time, so that the leaf environment is not disrupted significantly.

PM-48M SYSTEM CONSOLE Contains a built-in datalogger and CO2 Analyzer. Initiates measurement automatically immediately after power is on. Automatically operates with a set of 4 leaf chambers as well as 4 corresponding reference probes.

  The RS232 port is used for communicating with  PC. Terminal emulator software allows to  make necessary system settings and download the data for further processing and analysis in electronic worksheets (Excel, for instance)


AC Power adapter 220 V DC



Time diagram of the measuring cycle


T1 pumping air from a reference probe through the CO2 Analyzer. Recording current CO2 concentration at the end of T1 period.  Air flows through both reference and leaf chamber channels while only the reference air is forwarded to the analyzer.

T2 pumping air from a leaf chamber channel through CO2 Analyzer. Recording current CO2 concentration at the end of T2 period.

T3 - the measuring cycle for all 4 chambers.

Typical values are the following: T1=150 sec, T2=180 sec; T3=30 min.



Queuing chamber

Working chamber


Useful forms of data presentation  

        Diurnal curves of CO2 exchange as well as all relevant values measured with the use of optional sensors

        Diurnal light curve of photosynthesis (with the use of optional solar irradiance sensor)

        Daily CO2 balance of leaves



        Daily estimation of productivity and its evolution in time.

        Estimating contribution of different leaves to whole plant productivity.

        Comparing productivity of several plants of different varieties, or under different treatments.

Determining factor, which limits productivity



Potential Users


        Researchers in Crop Physiology and Horticulture

        Students of Agricultural Universities and Colleges

        Agricultural Engineers

        Agricultural Consultants & Extension Service

        Advanced Growers


An Example

Typical daily photosynthesis curve, obtained from tomato plants is displayed below.

The daily-accumulated values are approximately the same.




1.      LC-4A Leaf Chambers

Type: Self-clamping, normally opened
Type of suitable photosynthesis system: open
Drive: Pneumatic auto synchronized
Clap square: 20 cm2
Typical measuring time: 3 min
Suitable connecting hose diameter: 4 mm


2.      PM-48MB System Console

Specially designed for LC-4A type leaf chambers


      Air pump

      Valves for operating leaf chambers

      Air flow meter

      CO2 Analyzer

      Data logger

      RS 232 communication interface
Number of inputs for leaf chambers: 4
Number of the reference inputs : 4
Air flow meter: Range: 30...80 lph
Resolution: 1 lph
Nominal air flow rate: 35 lph
Full automated operation
Power requirements: 220 V AC; 2 A max.



Specifications are subject to change without notice.


May 2002



3.      CO2 Analyzer

Type: SBA-1 (PP Systems, UK)
Range of measurement: 0...1000 ppm typical
Resolution: 2 ppm typical
Signal noise at 350 ppm: 2 ppm typical

4.      Stand for positioning and fixing the leaf   chambers
Height: 1 m typical
Stainless steel and aluminum

5.      Power supply

220 V AC

6.      Terminal Emulator Software for  PC compatibles


      Communicating with PM-48M

      Interface for measurement settings

      Downloading data to PC

      Data file format is suitable for importing into Microsoft Excel