Q-Box CO650 Plant CO2 Analysis

The Q-Box CO650 Plant CO2 Analysis Package has been designed for measurements of photosynthesis, respiration and transpiration in leaves when placed in a flow-through leaf chamber. You can use Plant CO2 Analysis Package in both the lab or field (with optional battery pack). When you combine Q-Box CO650 with 4 channel Gas Switching System You can monitor photosynthesis, respiration and transpiration on up to 3 leaves (channel 1 is a reference).  NEW! the Q-Box CO650 has been enhanced to include automated reference checking and on-the-go calculations of photosynthesis and transpiration rates.

Photosynthesis and Respiration

Operation of the Q-Box CO650 Plant CO2 Analysis Package employs the use of one infrared CO2 gas analyzer (Q-S151). The concentration of CO2 gas entering a leaf chamber and exiting it, is measured at different times with the same analyzer. User specified control of the solenoid valve assembly switches between reference and sample measurements.  When the leaf is exposed to light the difference between influx and efflux CO2 levels (differential CO2), plus measurement of the gas flow through the chamber, allow automatic calculation of photosynthetic CO2 fixation rate.  Measurements of CO2 exchange in the dark provide data of dark respiration.


The Q-Box CO650 includes a Humidity/Temperature sensor (Q-S161) which measures relative humidity of the air before and after it has passed through the leaf chamber.  At the same time,  temperature at the RH sensor is also measured. The RH differential between influx and efflux gas, the temperature, the flow rate through the leaf chamber and leaf temperature are used in automatic calculation of leaf transpiration rates.

Light and Temperature

An LED Light Source (A113) supplies photosynthetically active radiation to the leaf with minimum heat load. The LED light source can deliver approximately 1200 µmol photons/m2/s at maximum output and it is supplied calibrated (in the software). As a result light intensity can be accurately set without the use of a light meter. For calculations of leaf conductance, leaf temperature measurements are required and these are obtained by the S173 Leaf Thermistor that is fitted in the bottom portion of the leaf chamber. The same thermistor can also measure air temperature inside the leaf chamber when not touching the leaf. Analog signals from all of the sensors are converted to digital signals via two integrated LabQuest mini interfaces (6 channels). Data is displayed, recorded and manipulated on a PC or Macintosh computer using Logger Pro software. Your Package comes with customized experimental files for data collection, automated calculations and any further analysis.

For Multichannel measurements of photosynthesis and transpiration consider adding QUBIT GAS SWITCHING SYSTEM to Q-Box CO650 Plant CO2 Analysis Package

  • Modular Gas Exchange Measuring System
  • Components interchangeable with other Q-Box Packages
  • Automated calculations of carbon and water exchange rates
  • Housed in rugged box for easy transport and set up
  • Use in a lab or Field (with optional battery pack)

Q-Box CO650 Software

Sample of raw data from spiderplant leaf

Automatic Calculations of Photosynthesis and transpiration (Page 2 in software)

Dr. Janice M. Coons, Professor of Botany, Biological Sciences Department, Eastern Illinois University, Charleston, IL

“We first started using the Qubit photosynthesis package shortly after I began teaching Plant Physiology in 1998. Initially, we purchased one package, and it worked so well that we soon added three more. Since that time, my class has used the system for two labs each semester including one that deals with photosynthesis and one that deals with respiration. During this time, we only had to upgrade the original sensors once…so their durability and long-lasting performance is remarkable. So I was able to get nearly 13 years of use from the initial packages that I purchased….even with hundreds of students using them! Their system is very student friendly, and performs very well in a classroom situation. Students are excited to see real-time measurements, and the software allows them to calculate rates very easily. Hence, the quality of their product is truly exceptional.