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Publication
Responses to water stress in two Eucalyptus globulus clones differing in drought tolerance
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Advisor(s)
Abstract(s)
We evaluated drought resistance mechanisms in a
drought-tolerant clone (CN5) and a drought-sensitive clone
(ST51) of Eucalyptus globulus Labill. based on the responses
to drought of some physiological, biophysical and morphological
characteristics of container-grown plants, with particular
emphasis on root growth and hydraulic properties. Water loss
in excess of that supplied to the containers led to a general decrease
in growth and significant reductions in leaf area ratio,
specific leaf area and leaf-to-root area ratio. Root hydraulic
conductance and leaf-specific hydraulic conductance decreased
aswater stress became more severe. During the experiment,
the drought-resistant CN5 clone maintained higher leaf
water status (higher predawn and midday leaf water potentials),
sustained a higher growth rate (new leaf area expansion
and root growth) and displayed greater carbon allocation to the
root system and lower leaf-to-root area ratio than the droughtsensitive
ST51 clone. Clone CN5 possessed higher stomatal
conductances at moderate stress as well as higher hydraulic
conductances than Clone ST51. Differences in the response to
drought in root biomass, coupled with changes in hydraulic
properties, accounted for the clonal differences in drought tolerance,
allowing Clone CN5 to balance transpiration andwater
absorption during drought treatment and thereby prolong the
period of active carbon assimilation.
Description
Keywords
Acclimation Allocation Hydraulic properties Root growth Water stress
Citation
Tree Physiology, 24, 1165-1172