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ABSTRACT: The chlorophyll (Chl) fluorescence induction kinetics, net photosynthetic CO2 fixation rates P N, and composition of photosynthetic pigments of differently light exposed leaves of several trees were comparatively measured to determine the differences in photosynthetic activity and pigment adaptation of leaves. The functional measurements were carried out with sun, half-shade and shade leaves of seven different trees species. These were: Acer platanoides L., Ginkgo biloba L., Fagus sylvatica L., Platanus x acerifolia Willd., Populus nigra L., Quercus robur L., Tilia cordata Mill. In three cases (beech, ginkgo, and oak), we compared the Chl fluorescence kinetics and photosynthetic rates of blue-shade leaves of the north tree crown receiving only blue sky light but no direct sunlight with that of sun leaves. In these cases, we also determined in detail the pigment composition of all four leaf types. In addition, we determined the quantum irradiance and spectral irradiance of direct sunlight, blue skylight as well as the irradiance in half shade and full shade. The results indicate that sun leaves possess significantly higher mean values for the net CO2 fixation rates P N (7.8-10.7 μmol CO2 m(-2) s(-1) leaf area) and the Chl fluorescence ratio R Fd (3.85-4.46) as compared to shade leaves (mean P N of 2.6-3.8 μmol CO2 m(-2) s(-1) leaf area.; mean R Fd of 1.94-2.56). Sun leaves also exhibit higher mean values for the pigment ratio Chl a/b (3.14-3.31) and considerably lower values for the weight ratio total chlorophylls to total carotenoids, (a + b)/(x + c), (4.07-4.25) as compared to shade leaves (Chl a/b 2.62-2.72) and (a + b)/(x + c) of 5.18-5.54. Blue-shade and half-shade leaves have an intermediate position between sun and shade leaves in all investigated parameters including the ratio F v/F o (maximum quantum yield of PS2 photochemistry) and are significantly different from sun and shade leaves but could not be differentiated from each other. The mean values of the Chl fluorescence decrease ratio R Fd of blue-shade and half-shade leaves fit well into the strong linear correlation with the net photosynthetic rates P N of sun and shade leaves, thus unequivocally indicating that the determination of the Chl fluorescence decrease ratio R Fd is a fast and indirect measurement of the photosynthetic activity of leaves. The investigations clearly demonstrate that the photosynthetic capacity and pigment composition of leaves and chloroplasts strongly depend on the amounts and quality of light received by the leaves.
Photosynthesis Research 05/2013; · 3.24 Impact Factor
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BMC Plant Biology. 01/2005;
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ABSTRACT: The differences in pigment levels, photosynthetic activity and the chlorophyll fluorescence decrease ratio R (Fd) (as indicator of photosynthetic rates) of green sun and shade leaves of three broadleaf trees (Platanus acerifolia Willd., Populus alba L., Tilia cordata Mill.) were compared. Sun leaves were characterized by higher levels of total chlorophylls a + b and total carotenoids x + c as well as higher values for the weight ratio chlorophyll (Chl) a/b (sun leaves 3.23-3.45; shade leaves: 2.74-2.81), and lower values for the ratio chlorophylls to carotenoids (a + b)/(x + c) (with 4.44-4.70 in sun leaves and 5.04-5.72 in shade leaves). Sun leaves exhibited higher photosynthetic rates P (N )on a leaf area basis (mean of 9.1-10.1 micromol CO(2) m(-2 )s(-1)) and Chl basis, which correlated well with the higher values of stomatal conductance G (s) (range 105-180 mmol m(-2 )s(-1)), as compared to shade leaves (G (s) range 25-77 mmol m(-2 )s(-1); P (N): 3.2-3.7 micromol CO(2) m(-2 )s(-1)). The higher photosynthetic rates could also be detected via imaging the Chl fluorescence decrease ratio R (Fd), which possessed higher values in sun leaves (2.8-3.0) as compared to shade leaves (1.4-1.8). In addition, via R (Fd) images it was shown that the photosynthetic activity of the leaves of all trees exhibits a large heterogeneity across the leaf area, and in general to a higher extent in sun leaves than in shade leaves.
Photosynthesis Research 93(1-3):235-44. · 3.24 Impact Factor
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ABSTRACT: It is shown that with a new flash-lamp chlorophyll (Chl) fluorescence imaging system (FL-FIS), the photosynthetic activity of several thousand points of an intact attached leaf can be screened in a non-destructive way within a few seconds. The method allows the detection of the gradients in photosynthetic capacity over different parts of the leaf. The photosynthetic activity is sensed via imaging the Chl fluorescence at its maximum Fm and at steady state Chl fluorescence Fs of the induction kinetics and by the subsequent determination of the image of the fluorescence decrease ratio (RFd) which is known as the vitality index of the photosynthetic apparatus. Under water stress the photosynthetic activity decreases as seen in the images of the two fluorescence ratios RFd and Fm/Fs. Histogram and profile analysis of Chl fluorescence images and Chl fluorescence ratios allow the quantification of the differences between normal and stressed leaves with a high statistical significance.
Plant Physiology and Biochemistry.
