The relative contribution of elastic and osmotic adjustments to turgor maintenance of woody species.

Abstract

1994. The relative contribution of elastic and osmotic adjustments to turgor maintenance of woody species. -Physiol. Plant. 90; 408-413.To determine how tissue water relations vary and contribute to turgor maintenance in species from contrasting ecological zones, seedlings of jack pine {Pinus banksiana Lamb.), black .spruce iPicea mariana |Mill) B.S.P.I and flooded gum (Eucalyptus grandis W. Hilt ex Maiden) were subjected to an 8 day drought stress by water withholding with and without prior mild water stress conditioning. Jack pine, a deep-rooted species from dry, sandy boreal sites, lost turgor at the low est relative water content (75-659^) and water potential, and had lowest maximum bulk elastic mtxlulus te^.,, of 5.2-5.S MPa). Although this suggests a high inherent dehydration tolerance, jack pine did not further adjust its elasticity when repeatedly stressed. Black spruce, a shallow-rooted species from predominantly moist sites in the boreal region, lost turgor at intermediate relative water content (86^769!) and water potential, but could adjust its elasticity to maintain turgor in repeatedly stressed tissues. Flooded gum, a deeprooted species from moist, warm temperate-subtropical regions, had a low inherenl drought tolerance since it lost turgor a! higher relative water content (88-849r) and water potential, but was capable of some adjustment when the stress was repeated. Elastic adjustment (<3.7 MPa) was more important for turgor maintenance than osmotic adjustment (<0.i3 MPa). which was statistically nonsignificanE. Maximum bulk modulus of elasticity, but not o.smotic potentials at full turgor, was significantly correlated with the relative water content and water potential at zero turgor in droughted seedlings. These results highlight the importance of tissue shrinkage for dehydration tolerance. Both the inherent capacity for turgor maintenance of a spKcies under drought and its ability to adjust to repeated drought .should be considered in genetic selections for drought tolerance.

Exploring drought tolerance in coffee: a physiological approach with some insights for plant breeding

“…Furthermore, development of increased leaf water deficits upon discontinuing irrigation may circumstantially be more rapid (or severe) in genotypes having greater amplitude of OA (Meinzer et al, 1990b;DaMatta et al, 1993). These observations imply that OA may not be an effective mechanism of drought tolerance in coffee, as has also been reported for several other woody species (Fan et al, 1994).…”

Respuesta fisiológica y de crecimiento en plantas de Quillaja saponaria y Cryptocarya alba sometidas a restricción hídrica

“…Los cambios requeridos a nivel de paredes celulares para llevar a cabo el ajuste elástico, que son mencionados por Zwiazek (1991), podrían explicar una respuesta de más largo plazo en el módulo de elasticidad. Si bien el ajuste osmótico y el ajuste elástico no se desarrollan en conjunto, o tienden a asumir uno mayor relevancia sobre el otro (Fan et al 1994), ambos mecanismos requieren de posteriores estudios que aclaren la participación de estos en la regulación de la turgencia en peumo.…”

Water relations of cork oak (Quercus suber L.) seedlings in response to shading and moderate drought

“…A lower cell wall elasticity would allow leaf water potential to drop rapidly and substantially as soon as the leaves began to loose water [34,38] and a rapid recovery after a decrease in soil water content, which is shown as an efficient mechanism to overcome water stress [14]. It has been suggested that a higher ε max value increases water absorption in a drying soil by increasing the soil-plant water potential gradient [18]; although both lower and higher elasticity have been suggested as promoting turgor maintenance.…”