Thermography and Chlorophyll Fluorescence Imaging Methods for Stress Evaluation

Thermography and chlorophyll fluorescence imaging methods are useful techniques to evaluate environmental effects on plant performance. Thermography, or infrared imaging (IR), has become less expensive and more precise in the last decade.  Modern IR cameras can resolve 0.1 to 0.5 °C temperature differences and research grade instruments can resolve 0.05 °C. This precision has allowed physical processes of freezing and transpiration to be more accurately studied and modeled. Chlorophyll fluorescence imaging, while still an expensive technology, has become sufficiently rugged to be useful in the field. The measurement of quantum efficiency, Fv/Fm, provides clear data on the effect of various environmental and biotic effects on the performance of photosynthesis in plants via the effect on photosystem II.  Modern digital cameras with low signal:noise ratios can also image gross chlorophyll fluorescence using time lapse exposure.  Peltier-cooled CCD cameras can measure the auto luminescence in stressed plants that is generated by reactive oxygen species. Technology has brought the cost and precision of imaging equipment to a point that they are useful tools to plant scientists.