Visualizing Plant Metabolism in IR
Plant physiology is a further topic of instruction that can be supported with the use of an IR camera. One clear example is investigating temperature variation of plant leaves due to stomatal regulation.
In agriculture, studying the response of crops to drought, fertilizers,
or genetic manipulation is an important application of thermal imaging, either in laboratory conditions or through remote sensing in
aerial observations with drones and helicopters (Jones, 2004; Costa
et al., 2013). As part of undergraduate teaching of energy-related
aspects of photosynthesis and cellular respiration, Donovan et al.
(2013) have introduced students to IR images of titan arum (corpse
flowers) that exhibit higher temperatures than their surroundings.
An increase in plant metabolism produces foul odors to attract pollinators to a mimicked rotten-meat smell that is associated with a significant temperature increase while the spathe opens. In applying
handheld IR cameras to biology education contexts, Xie (2012) has
demonstrated that fresh leaves and dry leaves have the same temperature in conditions where they have reached thermal equilibrium
with the surrounding air. However, the leaves of well-watered plants
can exhibit temperatures considerably lower than the surroundings.
In addition, in a process known as the Iwanov effect (Jones, 2004),
severing the leaves from a plant induces cooling of the leaf surface
as stomata initially open rapidly due to a water deficit (see Figure 3).
As part of the NGSS disciplinary core idea From Molecules to
Organisms: Structures and Processes, high school students are
expected to develop an understanding of energy transfer and transformation involved in cellular respiration and how organisms maintain their temperature. Visualizing such processes with thermal
cameras provides interesting learning opportunities for practical
inquiry-based approaches to the content area.
Handheld IR cameras offer new pedagogical opportunities to study
thermal phenomena in biology education. The technology is well
suited to identifying and visualizing differences and changes in sur-
face temperatures, which is difficult to accomplish with conven-
tional classroom and laboratory thermometers. The described IR
camera activities emphasize the cross-disciplinary nature of the
NGSS, particularly in relation to the crosscutting concept Energy
We are grateful for our discussions with Charles Xie on the application of IR cameras in education, and for our collaboration with
Elisabet Mellroth. We thank the teachers and students at the Lillerudsgymnasiet high school for demonstrating how IR technology
can be used in exploring equine physiology in education.
Costa, J.M., Grant, O.M. & Chaves, M.M. (2013). Thermography to explore
plant–environment interactions. Journal of Experimental Botany, 64,
Donovan, D.A., Atkins, L.J., Salter, I. Y., Gallagher, D.J., Kratz, R.F., Rousseau, J.
V., et al. (2013). Advantages and challenges of using physics curricula
as a model for reforming an undergraduate biology course. CBE—Life
Sciences Education, 12, 215–229.
Haglund, J., Jeppsson, F., Hedberg, D. & Schönborn, K.J. (2015). Thermal
cameras in school laboratory activities. Physics Education, 50, 424–430.
Jeppsson, F., Frejd, J. & Lundmark, F. (2017). “Wow, it turned out red! First,
a little yellow, and then red!” 1st-graders’ work with an infrared
camera. Journal of Research in Childhood Education, 31, 581–596.
Jones, H.G. (2004). Application of thermal imaging and infrared sensing in
plant physiology and ecophysiology. Advances in Botanical Research,
Kubsch, M., Nordine, J. & Hadinek, D. (2017). Using smartphone thermal
cameras to engage students’ misconceptions about energy. Physics
Teacher, 55, 504–505.
Figure 3. Thermal images taken with a FLIR C3 camera of a leaf surface one minute (left) and 25 minutes (right) after the leaf was
severed from a plant. The image on the right displays the temperature decrease due to rapid initial stomatal opening (and
consequent increased transpiration) as a physiological stress response to water deficit.