Infrared Gas Analysis (IRGA) Training

School of Biological and Physical Sciences (SBPS) organized and conducted an Infrared Gas Analysis (IRGA) training course. The training was coordinated by Prof. Dennis O. Ochuodho and was conducted by Mr. Daniel Okach from the University of Bayreuth, Germany, who has a verse experience with the equipment. Infrared gas analysis is a modern technique for quantifying the concentrations of diatomic gases. These include carbon dioxide (CO2), water (H2O) and other gases, which absorb the infrared rays. This principle has been applied in the quantification of CO2 and H2O exchange in plants and natural ecosystems. Key greenhouse gases that contribute to the current global warming can now be effectively quantified in real time. A series of equipment have been developed based on this principle and the two leading companies in this regard are the LI-COR of USA with its LI-COR 7500 and the WALZ GmbH of Germany with its GFS 3000 series.

These two sets of equipment are very comparable in their output results, with minor differences. Apart from the plant functions, the two sets are also able to deliver precise microclimatic data around the leaf during measurements, which make it possible to identify the actual driving variables of plant processes. They also have the advantage that the measurement head can be changed to suit the measurement conditions, including leaf types, leaf sizes, plant functions, etc. The sensor head can also be adopted to measure various parameters, including leaf gas exchange, leaf chlorophyll content, and leaf enzymatic functions, among others. The knowledge is valuable in botany, forestry, agriculture and other plant and environment management sciences. Most of our local universities suffer from the lack of such modern equipment, a fact that has slowed down the development of experimental plant sciences.

Some of the course participants conducting gas exchange measurements -A hands-on experience with GFS 3000 IRGA system.

Jaramogi Oginga University of Science and Technology endeavors to offer quality education to its students, through acquisition of some of the state-of the art instrument. It is on this background that the school of Biological and Physical Sciences organized a two-day training program on Infrared Gas Analysis, using the modern GFS 3000, WALZ GmbH, to its post graduate students and the technical staff.

The two-day training course was opened by Prof. Regina Nyunja, Dean School of Biological and Physical Sciences. In her words, the Dean emphasized the value of modern instrumentation in sciences. She stated that the science in Africa has lagged behind due to lack of equipment and encouraged the young doctoral students to consider changing the situation in the future. The availability of GFS 3000 in the school offers a unique opportunity to advance in science.

Dean, School of Biological and Physical Sciences, Prof. Regina Nyunja opening the GFS-3000 IRGA training Session.

The success of Infrared Gas Analysis (IRGA) technique is based on the properties of diatomic gas molecules, which make them able to absorb infra-red rays. The analyzer is built on the principle of direct proportionality between IR absorbance and concentrations of the sample diatomic gas, in our case CO2 or H2O. A known concentration of IR rays is emitted from an IR source, mostly an impregnated, high voltage tungsten wire. The rays are then directed through a gas cell filled with sample gas before the balance IR is counted at the end of the cell. For the purpose of estimating leaf or ecosystem CO2/H2O exchange processes, a second reference cell is introduced so that the difference in IR counts gives the rate of photosynthesis/respiration/transpiration. The modern IRGA however goes beyond this as it can provide accurate information on the microclimate around a leaf, information on the internal CO2 concentration of a leaf, leaf temperature, leaf chlorophyll content, stomatal conductance and many more details about the leaf sample in question. In plant biology, a leaf is regarded as the basic functional unit, while the other organs such as stems, fruits etc. are mainly for storage, support or water plumbing systems. Thus, as long we are able to stand leaf processes and function, we understand the entre plant and by extension the ecosystem. Participants had an opportunity to assemble the equipment together and to replace the different components used for various measurements.

Basic design of an infrared (IR) gas analyzer. A modern IRGA such as GFS 3000 or LI-6400XT incorporates more features to this basic design in order to gain more information of the leaf and its environment.



A unit of GFS-3000 IRGA from WALZ, Germany displaying some of the equipment parts used for different functions and measurements



Data processing session: Course participants working on data obtained with GFS 3000 IRGA