University of Groningen
Energy metabolism in higher plants in different environments
Lambers, Johannes Theo
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Publication date:
1979
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Lambers, J. T. (1979). Energy metabolism in higher plants in different environments Groningen: s.n.
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Summary
Respiration
in plants has been the subject of many
papers since Pasteurts early work at the end of the previous century. However, it is only since the last few
years that the efficiency
utilization
in
of assimilate
growth processes has been thoroughly investigated.
The
present research work was carried out to gain insight
into
(in roots of) higher plants:
the efficiency
of respiration
how many assimilates
are respired
to produce energy for
growth ('growth respirationt),
how many are respired for
maintenance processes (rmaintenance respirationt)
and to
twastefulr?
what extent is respiration
Chapter 2 describes a method to determine tgrowth respirationt
and the rrate of maintenance respirationt.
This
method was used for two Seneczo species.
Both growth respiration
and the rate of maintenance respiration
are higher
in roots of Seneci.o aquatícus
than in roots of S. jacogror,rn in
baea. Root growth respiration
of 5. aquqtíeus,
an aerated culture
was higher
than that of
solution,
plants
gro\^rn in a culture
solution
of low oxygen concentrat ion.
In chapter 3 the above mentioned differences
in growth
respiration
are further
analyzed. An roverflow
modelt is
proposed to explain the difference
in growth respiration
between the two species. The difference
in growth respigro\',m under different
ration
of S. aquaticus
environmental
conditions
is explained by a difference
in the contribution
of a non-phosphorylative
transport
electron
chain ('wasteful respirationr)
to respiration
under the different
experimental conditions.
No correlation
was observed between
the degree of wasteful respiration
and the flood tolerance
of species.
Chapter 4 describes investigations
on the nature of
flood tolerance
in some Seneclo species. It is concluded
that oxygen transport
from the aerial
parts to the roots
is a prerequisite
to tolerate. a root environment of a low
oxygen concentration.
In S. aquatíc?,is, metabolic
adaptations also
appear to be of significance.
Chapter 5 describes
experiments on growth respiration
and the rate of maintenance respiration
in shoots of
Senecio species.
It is concluded that the shoots of these
species use less respiratory
energy for growth than the
t7|
roots of the samespecies. This is partly ascribed to the
absence of an active alternative
oxidative pathway
(rrnrasteful respirationt)
in shoots of these species, which
show a high activity
of this pathway in the roots. In
photosynthetically
produced ATP may have conaddition,
of shoot growth respiration.
tributed to the efficiency
Chapter 6 gives a survey of root growth respiration
and the rate of mainLenance respiration
in several Senecio
and Plantago species and also a few other species. This
survey was made in order to obtain information on a possib1e ecological significance of wasteful root respiration.
is concluded that wasteful root respiration
It
is not of
direct advantage to a plant in adaptation to its soil
environment. The results indicate
that wasteful root
respiration depends on an imbalance between utilization
of sugars for synthesis of root material with transport of
sugars from the shoot to the root.
Chapter 7 gives a brief review of the biochemistry
pathway (tcyanide resistant respiration'
of the alternative
and the various explanations for its physiological
significance, described in the literature.
0n the basis of
results from the present study, it is concluded that the
alternative
chain in roots of higher plants is significant
in oxidation of the sugars that are imported to the roots
and that can not be used for energy production,
structural
growth and storage. In some tissues the alternative
chain
may be significant
in heat production, ethylene biosynthesis, etc.
Chapter 8 describes experiments that were done to obtain information on the regulation of root growth by light
intensity.
It is concluded to be unlikely that light
regulates the root growth rate of PLantago LanceoLata
ar;rdZea mays vía its effect on photosynthesis.
However, an
alternative
explanaÈion is not given, although it is excluded that light regulates the rate of dry matter accumulation of the roots via its effect on transpiration and
its subsequent effect on the removal of inhibitors,
produced locally,
of lateral root gror^/th. Light intensity,
however, aDpears to affect root morphology via its effect
on the rate of transpiration.
In chapter 9 the present results are discussed in relation to data from the literature
and a survey is given
on the effects of several environmental conditions on
growth and energy metabolism in roots of higher,plants.
In chapter l0 some aspects of the regulation of growth
rate and shoot to root ratio in higher plants are discussed.
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