Geoscience Reference
In-Depth Information
High heat
dissipation
High irradiance
Xanthophylls
de-epoxidation
Antenna
Relatively
low FS
Reaction
center
High ∆pH
Excitation pressure
on RC lowered
Increased electron
transport to O
2
photorespiration and
Mehler reaction
Qa
ETR maintained
or reduced
NADPH
NADPH
use limitation
NADP
Low CO
2
assimilation
Correlation
Stomatal closure
Water stress
FIGURe 14.5
The relationship between Fs and stomatal
conductance provides a method for remote sensing stress.
(Adapted from Medrano, H., Escalona, J. M., Boto, J., Gulias,
J., Flexas, J. 2002. Regulation of photosynthesis of C3 plants in
response to progressive drought: Stomatal conductance as a
reference parameter.
Ann. Bot.
89, 895-905.)
survival. Cold acclimation in nature is induced in the early
autumn by exposure to short days and non-freezing, chilling
temperatures, which combine to stop growth. A diffusible factor
that promotes acclimation, most likely ABA, moves from leaves
via the phloem to overwintering stems. ABA accumulates during
cold acclimation and is necessary for this process.
Cold acclimation and the development of maximum freez-
ing tolerance in overwintering herbaceous plants such as winter
wheat, winger rye, spinach and
Arabidopsis thaliana
require
active growth and development at low temperature. As a result,
leaves of these plant species developed at low temperatures
are anatomically, morphologically, physiologically and bio-
chemically distinct from the same plants developed at warm
temperatures. For example, these herbaceous species grown at
low temperatures exhibit a short, compact growth habit, thicker
leaves due to an increase in leaf mesophyll cell size and an
increase in the number of palisade cell layers, an increase in
