This title appears in the Scientific Report :
2005
Please use the identifier:
http://hdl.handle.net/2128/488 in citations.
Temporal and spatial patterns of growth and photosynthesis in leaves of dicotyledonous plants under long-term CO$_{2}$- and O$_{3}$-exposure
Temporal and spatial patterns of growth and photosynthesis in leaves of dicotyledonous plants under long-term CO$_{2}$- and O$_{3}$-exposure
The aim of this Ph.D. thesis was to investigate spatio-temporal effects of elevated [CO$_{2}$] and [O$_{3}$] on leaf growth and photosynthesis in dicotyledonous plants. High-resolution spatio-temporal patterns of leaf growth were measured with a digital image sequence processing method (DISP). For f...
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Personal Name(s): | Christ, Mareike Maja (Corresponding author) |
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Contributing Institute: |
Phytosphäre; ICG-III |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2005
|
Physical Description: |
VIII, 126 S. |
Dissertation Note: |
Universität Düsseldorf, Diss., 2005 |
ISBN: |
3-89336-406-4 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Chemie und Dynamik der Geo-Biosphäre |
Series Title: |
Schriften des Forschungszentrums Jülich. Reihe Umwelt / Environment
57 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
The aim of this Ph.D. thesis was to investigate spatio-temporal effects of elevated [CO$_{2}$] and [O$_{3}$] on leaf growth and photosynthesis in dicotyledonous plants. High-resolution spatio-temporal patterns of leaf growth were measured with a digital image sequence processing method (DISP). For further analysis with the DISP method, the accuracy and resolution was estimated. The results led to the conclusion that temporal courses of leaf RGR could be analyzed with a resolution of at least ]-h-means, while 24-h-means could be used for heterogeneity determination, that requires a high spatial resolution. Effects of elevated [CO$_{2}$] were investigated on $\textit{Populus deltoides}$ trees at Biosphere 2 Center, AZ, USA. After four years in elevated [CO$_{2}$] (800 and 1200 ppm), $\textit{Populus deltoides}$ did not show acclimation. In 1200 ppm, net CO$_{2}$ exchange rate was stimulated by a factor of 2-3 in growing leaves, accompanied by reduced stomatal conductance and transpiration rate, resulting in increased water use efficiency (WUE) by a factor of 2. Dark respiration was increased by a factor of ca. 1.5 in growing leaves. In high light, photosynthesis did not become CO$_{2}$-limited in elevated [CO$_{2}$]. Excess photosynthate was not completely used for leaf growth, which was accelerated but finally stimulated only by a factor of 1.2, resulting in an accumulation of starch in elevated [CO$_{2}$]. Relative leaf growth rate (RGR), which showed a clear diel rhythm, was reduced in the afternoon compared to ambient [CO$_{2}$], accompanied with a reduced concentration of glucose, the main carbohydrate for growth processes. Results indicate that glucose availability plays an important role in the control of decelerating growth stimulation in elevated [CO$_{2}$]. Furthermore, elevated [CO$_{2}$] increased heterogeneity of leaf RGR, presumably caused by reduced stomata] conductance, as an altered transpiration rate affects turgor and as such, growth. Increased patchiness of growth was accompanied by increased spatial heterogeneity of carbohydrate distribution, which is a further indication for the role of carbohydrates in growth processes. Experiments on the effects of elevated ozone ([O$_{3}$]) were performed on $\textit{Glycine max}$ at SoyFACE, IL, USA. Season-long elevation of [O$_{3}$] by 20 % above ambient concentration in the field led to a decreased leaf net CO$_{2}$ exchange rate of $\textit{Glycine max}$ of up to 30 % at the time of pod-fill, accompanied by a reduction of stomata] conductance. Effects were similar in growing and mature leaves, and leaf growth was slightly reduced, while yield remained unchanged. This might be explained by a shift of assimilates from vegetative to reproductive growth, as soluble carbohydrates were reduced in growing leaves by the end of the growing season. In mature leaves, however, starch accumulated, indicating altered sugar transport in elevated [CO$_{2}$]. In the growth chamber it could be shown that mild ozone stress (70 ppb, 6 h daily) increased the heterogeneity of leaf growth, which could have been caused by local damage of O$_{3}$, which entered the leaf through the stomata and likewise by the altered stomata] conductance. Experiments on cuttings of $\textit{Populus deltoides}$ showed that fluctuating environmental conditions increased spatial heterogeneity of leaf growth, and could alter the diel course of the leaf RGR, but did not change phasing completely. For $\textit{Populus deltoides}$, it could further be shown by growth and photosynthesis measurements, that veinal and vein-surrounding tissue develops faster than interveinal tissue. |