Laser-induced fluorescence emission signatures and spectral fluorescence ratios of terrestrial vegetation

The UV-laser induced fluorescence emission spectra (LIF signatures) of leaves with different chlorophyll and carotenoid content were recorded and the three fluorescence ratios blue/red (F450/F690), blue/green (F450/F530) and red/red (F690/F735) determined. The chlorophyll fluorescence ratio F690/F735 exhibited a curvilinear inverse relationship to the chlorophyll content. The fluorescence ratio F450/F530 reflects not only chlorophyll but also carotenoid content (linear relationship with the pigment ratio chlorophylls/carotenoids). The ratio blue/red (F450/F690) is very sensitive to environmental changes (e.g. to the high light intensity during growth of plants). From excitation spectra it is deduced that the UV-laser of a future lidar fluorosensor should excite in the wavelength range of 370 to 395 nm in order to equally excite the blue, green and red plant fluorescence