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@PHDTHESIS{Christ:45170,
author = {Christ, Mareike Maja},
title = {{T}emporal and spatial patterns of growth and
photosynthesis in leaves of dicotyledonous plants under
long-term {CO}$_{2}$- and {O}$_{3}$-exposure},
volume = {57},
school = {Universität Düsseldorf},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-45170},
isbn = {3-89336-406-4},
series = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
Environment},
pages = {VIII, 126 S.},
year = {2005},
note = {Record converted from VDB: 12.11.2012; Universität
Düsseldorf, Diss., 2005},
abstract = {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.},
cin = {ICG-III},
ddc = {333.7},
cid = {I:(DE-Juel1)VDB49},
pnm = {Chemie und Dynamik der Geo-Biosphäre},
pid = {G:(DE-Juel1)FUEK257},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/45170},
}