Recently, a new high resolution fluorescence imaging Nd:YAG laser system that allows fast and large scale screening of fluorescence gradients over the whole leaf surface was developed, jointly by physicists of Strasbourg-Groupe d'Optique Applique (GOA),France and plant physiologists of Karlsruhe-Botanisches II, Germany, for detection of vegetation stress. This system was used to remotely detect stresses in different kinds of plants, both under laboratory and field conditions.
Typical fluorescence images obtained from tobacco leaves, at the blue, green, red and far-red bands, subjected to water and temperature stress are shown below with the corresponding fluorescence image ratios. Due to the increase of chlorophyll fluorescence at the leaf rims, the fluorescence ratios blue/red(F440/F690) and blue/far-red(F440/F740) significantly decreased at the leaf rim with a gradient from the central leaf part with highest values, to the leaf rim with lowest values.
For further details see:
Lichtenthaler, H.K., Lang, M., Sowinska, M., Heisel, F. and Miehe, J.A., 1996, Detection of vegetation stress via a new high resolution fluorescence imaging system, J. Plant Physiol. , 148, 599-ól2.
Lichtenthaler, H.K., Subhash N., Wenzel, O. and Miehe, J.A., 1997b, Laser-induced imaging of blue/red and blue/far-red fluorescence ratios, F440/F690 and F440/F740, as a means of early stress detection in plants, Proc. Intl. Geoscience and Remote Sensing Symposium, Aug 3-8, Singapore, vol. IV, pp. 1799-1801.
