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 attached or detached leaves placed in a flow-through leaf chamber. The Plant CO2 Analysis Package can be used in both the lab or field (with optional battery pack).  When combined with the 4 channel Qubit Gas Switching System Q-Box CO650 can monitor photosynthesis, respiration and transpiration on up to 3 leaves (channel 1 is a reference).

Operation of the Q-Box CO650 Plant CO2 Analysis Package employs the use of an infrared CO2 gas analyzer (Q-S151) to measure, at different times, the concentration of CO2 in a gas entering a leaf chamber, and the concentration of CO2 in the same gas after it leaves the chamber. The difference between influx and efflux CO2 concentrations (differential CO2) when the leaf is exposed to light, plus a measurement of the flow of gas through the chamber, allow calculation of photosynthetic CO2 fixation rate.  The method can also be used to measure CO2 evolution from the leaf in the dark (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 plus temperature at the RH sensor. The RH differential between influx and efflux gas, the temperature, and the flow rate through the leaf chamber, allow calculation of leaf transpiration rates.

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) so 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 for measurements of leaf temperature during experiments. 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.

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
  • 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 detached leaf (Page 1 in software)

Calculation Template (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.