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  • 1
    Electronic Resource
    Electronic Resource
    Control of transpiration in three coffee cultivars: the role of hydraulic and crown architecture (2000)
    Springer
    Trees 14 (2000), S. 181-190 
    Details
    ISSN: 0931-1890
    Keywords: Key words  Coffee arabica ; Hydraulic conductance ; Sap flow ; Stomata ; Stomatal decoupling coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Water use and hydraulic architecture were studied in the coffee (Coffea arabica) cultivars San Ramon, Yellow Caturra and Typica growing in the field under similar environmental conditions. The cultivars differed in growth habit, crown architecture, basal sapwood area and total leaf surface area. Transpiration per unit leaf area (E), stomatal conductance (g s), crown conductance (g c), total hydraulic conductance of the soil/leaf pathway (G t) and the stomatal decoupling coefficient, omega (Ω) (Jarvis and McNaughton 1986) were assessed over a range of soil moisture and during partial defoliation treatments. The relationship between sap flow and sapwood area was linear and appeared to be similar for the three cultivars. Variation in g c, E, and G t of intact plants and leaf area-specific hydraulic conductivity (k l) of excised lateral branches was negatively correlated with variation in the ratio of leaf area to sapwood area. Transpiration, g c, and g s were positively correlated with G t. Transpiration and G t varied with total leaf area and were greatest at intermediate values (10 m2) of leaf area. Omega was greatest in Yellow Caturra, the cultivar with the greatest leaf area and a dense crown, and was smallest in Typica, the cultivar with an open crown. Differences in omega were attributable primarily to differences in leaf boundary layer conductance among the cultivars. Plants of each cultivar that were 40% defoliated maintained sap flows comparable to pretreatment plants, but expected compensatory increases in g s were not consistently observed. Despite their contrasting crown morphologies and hydraulic architecture, the three cultivars shared common relationships between water use and hydraulic architectural traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009762
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  • 2
    Electronic Resource
    Electronic Resource
    The impact of chronic disease on the family (2002)
    Oxford, UK : Blackwell Science Ltd
    Haemophilia 8 (2002), S. 0 
    Details
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary.  Haemophilia is a chronic disease, affecting patients and their families. The impact of such a disease upon each family is dependent upon family type and characteristics and adjustment to it varies with time, in concordance with the family's lifecycle. In the National Hemophilia Center in Israel we lead a special support system and conduct group therapy from the very early stage of haemophilia diagnosis throughout the lifetime of patients. The general definitions of a family's lifecycle, the effect of the disease and the required adjustment to it are described in this paper. We refer to special difficulties associated with haemophilia as a chronic, genetic disease and describe ways to cope, discussing the support systems that have been established in our centre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2516.2002.00642.x
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  • 3
    Electronic Resource
    Electronic Resource
    Whole-tree water transport scales with sapwood capacitance in tropical forest canopy trees (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The present study examines the manner in which several whole-tree water transport properties scale with species-specific variation in sapwood water storage capacity. The hypothesis that constraints on relationships between sapwood capacitance and other water relations characteristics lead to predictable scaling relationships between intrinsic capacitance and whole-tree behaviour was investigated. Samples of sapwood from four tropical forest canopy tree species selected to represent a range of wood density, tree size and architecture, and taxonomic diversity were used to generate moisture release curves in thermocouple psychrometer chambers, from which species-specific values of sapwood capacitance were calculated. Sapwood capacitance was then used to scale several whole-tree water transport properties determined from measurements of upper branch and basal sap flow, branch water potential, and axial and radial movement of deuterated water (D2O) injected into the base of the trunk as a tracer. Sapwood capacitance ranged from 83 to 416 kg m−3 MPa−1 among the four species studied and was strongly correlated with minimum branch water potential, soil-to-branch hydraulic conductance, daily utilization of stored water, and axial and radial movement of D2O. The species-independent scaling of several whole-tree water transport properties with sapwood capacitance indicated that substantial convergence in plant function at multiple levels of biological organization was revealed by a simple variable related to a biophysical property of water transport tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.01039.x
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamic changes in hydraulic conductivity in petioles of two savanna tree species: factors and mechanisms contributing to the refilling of embolized vessels (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Diel variation in specific hydraulic conductivity (ks) was recorded in petioles of two savanna tree species, Schefflera macrocarpa and Caryocar brasiliense, from central Brazil. These two species have compound leaves with long petioles (10–30 cm). In both species, petiole ks decreased sharply with increasing transpiration rates and declining leaf water potentials (ψL) during the morning. Petiole ks increased during the afternoon while the plants were still transpiring and the water in the non-embolized vessels was still under tension. Dye experiments confirmed that in both species diel variation in ks was associated with embolism formation and repair. When transpiration was prevented in individual leaves, their petiole ks and water potential remained close to their maximum values during the day. When minimum daily ψL on selected branches was experimentally lowered by 0.2–0.6 MPa, the rate of ks recovery during the afternoon was slower in comparison with control branches. Several field manipulations were performed to identify potential mechanisms involved in the refilling of embolized petiole vessels. Removal of the cortex or longitudinal incisions in the cortex prevented afternoon recovery of ks and refilling of embolized vessels. When distilled water was added to petiole surfaces that had been abraded to partially remove the cuticle, ks increased sharply during the morning and early afternoon. Evidence of starch to sugar conversion in the starch sheath cells surrounding the vascular bundles of the petioles was observed during periods of rapid transpiration when the abundance of starch granules in the starch sheath cells surrounding the vascular bundles decreased. Consistent with this, petiole sugar content was highest in the early afternoon. The most parsimonious explanation of the field observations and the experimental results was that an increase in osmotically active solutes in cells outside the vascular bundles at around midday leads to water uptake by these cells. However, the concurrent increase in tissue volume is partially constrained by the cortex, resulting in a transient pressure imbalance that may drive radial water movement in the direction of the embolized vessels, thereby refilling them and restoring water flow. This study thus presents evidence that embolism formation and repair are two distinct phenomena controlled by different variables. The degree of embolism is a function of tension, and the rate of refilling a function of internal pressure imbalances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0140-7791.2003.01082.x
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  • 5
    Electronic Resource
    Electronic Resource
    Stem water storage capacity and efficiency of water transport: their functional significance in a Hawaiian dry forest (2000)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We investigated the contribution of internal water storage and efficiency of water transport to the maintenance of water balance in six evergreen tree species in a Hawaiian dry forest. Wood-saturated water content, a surrogate for relative water storage capacity, ranged from 70 to 105%, and was inversely related to its morphological correlate, wood density, which ranged between 0·51 and 0·65 g cm−3. Leaf-specific conductivity (kL) measured in stem segments from terminal branches ranged from 3 to 18 mmol m−1 s−1 MPa−1, and whole-plant hydraulic efficiency calculated as stomatal conductance (g) divided by the difference between predawn and midday leaf water potential (ΨL), ranged from 70 to 150 mmol m−2 s−1 MPa−1. Hydraulic efficiency was positively correlated with kL (r2 = 0·86). Minimum annual ΨL ranged from − 1·5 to − 4·1 MPa among the six species. Seasonal and diurnal variation in ΨL were associated with differences among species in wood-saturated water content, wood density and kL. The species with higher wood-saturated water content were more efficient in terms of long-distance water transport, exhibited smaller diurnal variation in ΨL and higher maximum photosynthetic rates. Smaller diurnal variation in ΨL in species with higher wood-saturated water content, kL and hydraulic efficiency was not associated with stomatal restriction of transpiration when soil water deficit was moderate, but avoidance of low minimum seasonal ΨL in these species was associated with a substantial seasonal decline in g. Low seasonal minimum ΨL in species with low kL, hydraulic efficiency, and wood-saturated water content was associated with higher leaf solute content and corresponding lower leaf turgor loss point. Despite the species-specific differences in leaf water relations characteristics, all six evergreen tree species shared a common functional relationship defined primarily by kL and stem water storage capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00533.x
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  • 6
    Electronic Resource
    Electronic Resource
    Temporal and spatial partitioning of water resources among eight woody species in a Hawaiian dry forest (2000)
    Springer
    Oecologia 124 (2000), S. 309-317 
    Details
    ISSN: 1432-1939
    Keywords: Key words Resource partitioning ; Soil water uptake ; Stable isotopes ; Species diversity ; Tropical dry forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Lowland dry forests are unique in Hawaii for their high diversity of tree species compared with wet forests. We characterized spatial and temporal partitioning of soil water resources among seven indigenous and one invasive dry forest species to determine whether the degree of partitioning was consistent with the relatively high species richness in these forests. Patterns of water utilization were inferred from stable hydrogen isotope ratios (δD) of soil and xylem water, zones of soil water depletion, plant water status, leaf phenology, and spatial patterns of species distribution. Soil water δD values ranged from –20‰ near the surface to –48‰ at 130 cm depth. Metrosideros polymorpha, an evergreen species, and Reynoldsia sandwicensis, a drought-deciduous species, had xylem sap δD values of about –52‰, and appeared to obtain their water largely from deeper soil layers. The remaining six species had xylem δD values ranging from –33 to –42‰, and apparently obtained water from shallower soil layers. Xylem water δD values were negatively correlated with minimum annual leaf water potential and positively correlated with leaf solute content, an integrated measure of leaf water deficit. Seasonal patterns of leaf production ranged from dry season deciduous at one extreme to evergreen with near constant leaf expansion rates at the other. Species tapping water more actively from deeper soil layers tended to exhibit larger seasonality of leaf production than species relying on shallower soil water sources. Individuals of Myoporum sandwicense were more spatially isolated than would be expected by chance. Even though this species apparently extracted water primarily from shallow soil layers, as indicated by its xylem δD values, its nearly constant growth rates across all seasons may have been the result of a larger volume of soil water available per individual. The two dominant species, Diospyros sandwicensis and Nestegis sandwicensis, exhibited low leaf water potentials during the dry season and apparently drew water mostly from the upper portion of the soil profile, which may have allowed them to exploit light precipitation events more effectively than the more deeply rooted species. Character displacement in spatial and temporal patterns of soil water uptake was consistent with the relatively high diversity of woody species in Hawaiian dry forests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420000384
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