Growth, leaf morphology, water use and tissue water relations of Eucalyptus globulus clones in response to water deficit

Abstract

Changes in leaf size, specific leaf area (SLA), transpiration and tissue water relations were studied in leaves of rooted cuttings of selected clones of Eucalyptus globulus Labill. subjected to well-watered or drought conditions in a greenhouse. Significant differences between clones were found in leaf expansion and transpiration. There was a significant clone x treatment interaction on SLA. Water stress significantly reduced osmotic potential at the turgor loss point (Pi0) and at full turgor (Pi100), and significantly increased relative water content at the turgor loss point and maximum bulk elastic modulus. Differences in tissue water relations between clones were significant only in the mild drought treatment. Among clones in the drought treatments, the highest leaf expansion and the highest increase in transpiration during the experiment were measured in those clones that showed an early and large decrease in Pi0 and Pi100.

Drought conditioning improves water status, stomatal conductance and survival ofEucalyptus globulussubsp. bicostataseedlings

“…The simultaneous osmotic and elastic adjustments lead to a significant increase in Ψ p100 of stressed plants. Both mechanisms contribute to increase the Ψ w gradient between plant and soil, promoting water uptake at low soil water potential [32,46], in agreement with a previous report in potted-plants of E. globulus [34]. The lower tissue elasticity and the higher level of osmotic adjustment observed at the end of this stage compared to those detected at the preconditioning period, could be associated to the greater severity of the drought imposed after transplanting [16].…”

“…The lower tissue elasticity and the higher level of osmotic adjustment observed at the end of this stage compared to those detected at the preconditioning period, could be associated to the greater severity of the drought imposed after transplanting [16]. High bulk modulus of elasticity has been related to processes of cell maturation [34]. Decrease in tissue elasticity has been identified in several species of Eucalyptus as a mechanism contributing to turgor maintenance under drought conditions [15,56,57], and after drought periods during wintertime [15].…”

“…bicostata exposed to drought preconditioning experienced several changes in their physiological parameters. Plants of Tumbarumba provenance developed osmotic adjustment, a mechanism of drought adaptation in E. globulus [6,15,16,34,54]. This adaptive response to drought allows water to move into cells, thereby maintaining the pressure potential.…”

“…The decrease in total biomass, leaf area and shoot/root biomass ratio, as well as their physiological changes, can be associated with their drought hardening [7,16,34]. Small seedlings sometimes performed better than large plants under soil water deficit [21].…”

Variations saisonnières des hydrates de carbone, des cyclitols et des relations hydriques chez 3 espèces d’Eucalyptus de taxonomie contrastée, en plein champ et poussant sur un site commun

“…For eucalypts, the adjustment of internal osmotic potential in response to saline and/or dry conditions has been demonstrated across many species (ClaytonGreene, 1983;Lemcoff et al, 1994;Li, 1998;Myers et al, 1986;Pita et al, 2001;Tuomela, 1997;White et al, 2000). Variation among eucalypt species in the capacity to modify osmotic potential has been proposed to explain differing salt (Grieve et al, 1999) and drought (Li, 1998) tolerances, leading to suggestions of its use as a selection criterion (Lemcoff et al, 1994;van der Moezel et al, 1991).…”