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@PHDTHESIS{Nagel:46953,
author = {Nagel, Kerstin A.},
title = {{A}bhängigkeit des {W}urzelwachstums vom {L}ichtregime des
{S}prosses und deren {M}odifikation durch {N}ährstoffe
sowie im {G}ravitropismus},
volume = {63},
school = {Universität Düsseldorf},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-46953},
isbn = {3-89336-443-9},
series = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
Environment},
pages = {119 S.},
year = {2006},
note = {Record converted from VDB: 12.11.2012; Universität
Düsseldorf, Diss., 2006},
abstract = {The aim of this Ph.D. thesis was to characterise the
effects of light, also in combination with nutrient
availability or gravitropic response, on the growth dynamics
of Nicotiana tabacum. Seedling biomass, primary root growth
as well as sugar concentration in root and shoot increased
significantly with increasing light intensity (60 to 300
μmol m$^{-2}$ s$^{-1}$). To quantitatively analyse the
dynamics of root growth a digital image sequence processing
method with a high temporal and spatial resolution was
applied. Upon transition from low to high light intensities,
root growth increased continuously within four days,
reaching the steady-state level measured in plants that had
been cultivated in high-light conditions (300 μmol m$^{-2}$
s$^{-1}$). The entire root growth zone, and hence each phase
of cellular development, was affected very similarly by the
increasing light treatment. During the first three hours
after light increase, strong growth fluctuations were
observed repeatedly. While the first phase of the reaction
(0.5 h) could be attributed to hydraulic acclimation, the
second phase (2.5 h) could be ascribed to photosynthetic
acclimation. Experiments with externally applied sucrose and
with transgenic plants having reduced capacities for sucrose
synthesis indicated clearly that increasing light intensity
rapidly enhanced root growth by enhancing sucrose export
from shoot to root. High light intensity facilitated
increasing lateral root production under nutrient deficiency
some days earlier than low light conditions. This
demonstrates the tight and coordinated interaction between
carbohydrate and nutrient metabolism. By using two
Arabidopsis mutants, in which auxin-mediated signaling is
impaired, two spatially separated zones and motors of
curvature production in root tips were revealed after
rotating the plants by 90°. Only the second motor, which is
located more basal, seems to be auxin dependent. The
increase of curvature production of this motor after light
changing may be attributable to an increase of the
energy-dependent auxin-transport or to an enhancement of
circumnutation frequency. Due to the circumnutations,
leading to a transient curvature in the opposite direction
of gravitropic force, roots exhibited under low and high
light intensity 2.5 h after rotation by 90° comparable
curvature angles.},
cin = {ICG-III},
ddc = {333.7},
cid = {I:(DE-Juel1)VDB49},
pnm = {Terrestrische Umwelt},
pid = {G:(DE-Juel1)FUEK407},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/46953},
}