948 
fluorescence intensity [rel. units] 
wavelength [nm] 
Fig. 1. Blue-green and red fluorescence emission 
spectra sensed from the main leaf vein and from 
the intercostal field of the lower leaf-side of 
photosynthetically active leaves of Nicotiana 
tabacum L.. A. green form su/su, B. aurea mutant 
Su/su. The fluorescence was excited by UV-A 
radiation of 355 ± 5 nm. Mean value of 4 
determinations from 2 leaves, standard deviation 
in the four maxima or shoulders 7 % or less. 
wavelength [nm] 
B. 
7 6 5 4 3 2 1 
leaf region 
Fig. 2A.Three dimensional surface plot of the 
fluorescence emission spectra of different leaf 
parts of the lower leaf-side of Nicotiana tabacum 
L. aurea form Su/su. The spectra were measured 
in the intercostal fields of the leaf (regions No. 1 
to 3 and 5 to 7) and in the main leaf vein region 
(No. 4). B. Scanning image of the lower leaf-side 
of the tobacco leaf with indications of the leaf 
regions No. 1 to 7 from which the fluorescence 
emission spectra were sensed.