TopPlant, Cell & Environment Virtual Special Issue Library

Table of Contents

Higher rates of leaf gas exchange are associated with higher leaf hydrodynamic pressure gradients
Franks, PJ
Volume 29, Issue 4, Page 584-592 April 2006
The relationships between stomatal conductance, leaf hydraulic conductance, and water potential drawdown across the leaf were studied for ten species with varying photosynthetic capacities. Although leaf hydraulic conductance increased with stomatal conductance, the relationship was nonlinear, resulting in an higher water potential drawdowns for species with higher stomatal conductances.

Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats
Addington, RN; Donovan, LA; Mitchell, RJ; Vose, JM; Pecot, SD; Jack, SB; Hacke, UG; Sperry, JS; Oren, R
Volume 29, Issue 4, Page 535-545 April 2006
Longleaf pine trees growing in xeric sites were shorter and had higher root-leaf-area ratios than trees growing in mesic sites. These adaptations allowed trees in the two environments to have similar stomatal conductances and soil-to-leaf water potential gradients despite similar values of leaf-specific hydraulic conductivity and tissue-specific root hydraulic conductivity.

Functional coordination between leaf gas exchange and vulnerability to xylem cavitation in temperate forest trees
Maherali, H; Moura, CF; Caldeira, MC; Willson, CJ; Jackson, RB
Volume 29, Issue 4, Page 571-583, April 2006
Vulnerability to xylem cavitation in stems and roots was found to be negatively correlated with specific conductivity, stomatal conductance, and photosynthetic rate 14 tree species. These data suggest a trade-off between transport capacity and vulnerability, and highlight the role of roots in controlling plant water transport.

Diurnal and seasonal variation in root xylem embolism in neotropical savanna woody species: impact on stomatal control of plant water status
Domec, JC; Scholz, FG; Bucci, SJ; Meinzer, FC; Goldstein, G; Villalobos-Vega, R
Volume 29, Issue 1, Page 26-35, January 2006
Substantial diurnal embolism in root xylem was found in four neotropical tree species. The degree of embolism at midday was negatively correlated with maximum stomatal conductance, suggesting that diurnal embolism forms a part of a hydraulic signal between roots and shoots.

How do leaf hydraulics limit stomatal conductance at high water vapor pressure deficits?
Bunce, J
Volume 29, Issue 8, Page 1644, August 2006
Lowering the CO₂ concentration around leaves was used to cause an increase in stomatal conductance high leaf-to-air water vapor differences (D). This increase in conductance (and transpiration) did not cause a reduction in xylem hydraulic conductance. This result suggests that all stomatal responses to D are not associated with reduced hydraulic conductance. The data implications of the data are discussed with reference to mechanisms for the stomatal response to D.

Water relations of baobab trees (Adansonia spp. L.) during the rainy season: does stem water buffer daily water deficits?
Chapotin, SM; Razanameharizaka, JH; Holbrook, NM
Volume 29, Issue 6, Page 1021-1032, June 2006
Baobab trees store water in their trunks. Measurements of stomatal conductance, sap flow, and water potential show that stored water is used primarily for buffering seasonal water deficits rather than daily water deficits. Daily reductions in leaf water potential were found to be limited by stomatal closure.

Linking physiological processes with mangrove forest structure: phosphorus deficiency limits canopy development, hydraulic conductivity and photosynthetic carbon gain in dwarf Rhizophora mangle
Lovelock, CE; Ball, MC; Choat, B; Engelbrecht, BMJ; Holbrook, NM; Feller, IC
Volume 29, Issue 5, Page 793-802, May 2006
Phosphorous fertilization of mangrove trees caused increases in xylem vessel diameter, hydraulic conductivity, photosynthesis and stomatal conductance. An analysis of trait plasticity indentified hydraulic properties of trees as more plasitc than those of leaf structural and physiological characteristics, implying that hydraulic properties are key in controlling growth in mangroves.

Long-term acclimatization of hydraulic properties, xylem conduit size, wall strength and cavitation resistance in Phaseolus vulgaris in response to different environmental effectss
Holste, EK; Jerke, MJ; Matzner, SL
Volume 29, Issue 5, Page 836-843, May 2006
Xylem structural characteristics and hydraulic properties were measured for Phaseolus vulgaris plants grown under various environmental conditions. Dry and porous-soil conditions decreased vessel size and increased cavitation resistance. The authors discuss their results in light of current hypotheses concerning tradeoffs between safety and efficiency.

The hydraulic limitation hypothesis revisited
Ryan, MG; Phillips, N; Bond, BJ
Volume 29, Issue 3, Page 367-381, March 2006
The hydraulic limitation hypothesis proposes that tree height and wood production in tall trees is limited by stomatal closure in resposne to hydraulic limitations. The authors discuss the evidence for and against this hypothesis.

Ecological physiology of Pereskia guamacho, a cactus with leaves
Edwards, EJ; Diaz, M
Volume 29, Issue 2, Page 247-256 February 2006
Measurements of stomatal conductance and xylem hydraulic conductance suggest that leaf performance is not limited by stem hydraulics in this species. Water use was found to be tightly regulated at the leaf level.

Long-term hydraulic acclimation to soil texture and radiation load in cotton
Li, Y; Xu, H; Cohen, S
Volume 28, Issue 4, Page 492-499, April 2005
When soil texture or atmospheric evaporative demand varies, cotton plants were found to co-ordinate their capacities for liquid phase and vapour phase water transport through long-term acclimation of the hydraulic system, or plastic morphological adaptation of the root/leaf ratio.

Adaptation to high salinity in poplar involves changes in xylem anatomy and auxin physiology
Junghans, U; Polle, A; Düchting, P: Weiler, E; Kuhlman, B; Gruber, F; Teichmann, T
Volume 29, Issue 8, Page 1519, August 2006
Salt stress caused a greater decrease in xylem hydraulic conductivity for a salt-sensitive Populus species than for a salt tolerant species. Salt stress also caused a larger decrease in free auxin in the xylem for the salt sensitive species, but an increase in conjugated auxin. The role of auxin physiology in the response of these species to salt stress is discussed.

Evidence from Amazonian forests is consistent with isohydric control of leaf water potential
Fisher, RA; Williams, M; Lobo do Vale, R; Lola da Costa, A; Meir, P
Volume 29, Issue 2, Page 151, February 2006
A combination of modeling and experimental approaches shows that the dominant cause for stomatal closure under dry conditions in Amazonian trees in an decrease in soil-to-leaf hydraulic conductance.

Hydraulic efficiency and safety of branch xylem increases with height in Sequoia sempervirens (D. Don) crowns
Burgess, SSO; Pittermann, J; Dawson, TE
Volume 29, Issue 2, Page 229-239, February 2006
Xylem conductivity and safety increased with height in Sequoia sempervirens branches. These results are discussed with regard to safety-vs-efficiency tradeoffs and with regard to the hydraulic limitation hypothesis.