Über die Bedeutung des Hoftüpfelverschlusses für die axiale Wasserleitfähigkeit von Nadelhölzern

Hüber, Bruno; Merz, Walter

doi:10.1007/bf01885733

Cited by 23 publications

(5 citation statements)

References 30 publications

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“…2001) although the observation was already made by Zimmermann (1978) in a nice example of serendipity. Observing a decreasing flow rate of distilled water through a piece of stem (a problem already described by Huber & Merz 1958), Zimmerman hypothesized that tiny gas bubbles obstructed pit pores. Therefore he replaced the distilled water with tap water (assuming that tap water contained more bubbles than distilled water), but contrary to expectation the flow rate instantaneously increased.…”

Section: Low Resistance Allows High Water Flowsmentioning

confidence: 99%

Logistics of water and salt transport through the plant: structure and functioning of the xylem

Boer

Volkov

2003

Plant Cell & Environment

183

134

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The xylem is a long-distance transport system that is unique to higher plants. It evolved into a very sophisticated plumbing system ensuring controlled loading/unloading of ions and water and their effective translocation to the required sinks. The focus of this overview will be the intrinsic interrelations between structural and functional features of the xylem. Taken together the xylem is designed to prevent cavitation (entry of air bubbles), induced by negative pressures under transpiration and to repair the cavitated vessels. Half-bordered pits between xylem parenchyma cells and xylem vessels are on the one hand the gates to the vessels but on the other hand a serious 'bottle-neck' for transport. Hence it becomes evident that special transport systems exist at the interface between the cells and vessels, which allow intensive fluxes of ions and water to and out of the xylem. The molecular identification and biophysical/ biochemical characterization of these transporters has just started. Paradigms for the sophisticated mechanism of controlled xylem transport under changing environmental conditions are SKOR, a Shaker-like channel involved in K + -loading and SOS1, a Na + /H + antiporter with a proposed dual function in Na + transport. In view of the importance of plant water relations it is not surprising to find that water channels dominate the gate of access to xylem. Future studies will focus on the mechanism(s) that regulate water channels and ion transporters and on their physiological role in, for example, the repair of embolism. Clearly, progress in this specific field of research will greatly benefit from an integration of molecular and biophysical techniques aimed to understand 'whole-plant' behaviour under the everchanging environmental conditions in the daily life of all plants.

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Section: Low Resistance Allows High Water Flowsmentioning

confidence: 99%

Logistics of water and salt transport through the plant: structure and functioning of the xylem

Boer

Volkov

2003

Plant Cell & Environment

183

134

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“…One of the initial problems was that a piece of stem often gives a steadily decreasing flowrate withdistilled water-. This problem seems to have been first encountered by Huber and Merz (1958) who worked with coniferous wood. They ascribed this decrease to gradual closure of bordered pits.…”

Section: Rc~prorlrrcibility Of Resrrltsmentioning

confidence: 99%

Hydraulic architecture of some diffuse-porous trees

Zimmermann¹

1978

Can. J. Bot.

483

331

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The rate of flow of a dilute KCl solution through sections of stem, branches, and twigs was measured and expressed in microlitres per hour, under conditions of gravity flow, per gram fresh weight of leaves supplied by that section of xylem. This is called leaf-specific conductivity (LSC). It is not uniform throughout the tree, LSC of the stem being higher than that of branches. Furthermore, vascular junctions, such as the path from stem to branch, represent hydraulic constrictions. Distribution of LSC in the tree is primarily based on varying vessel diameters. Vessel diameters increase from top to bottom in the tree stem. They are smaller in branches than in the main stem, and there is a distinct constriction of diameters at the base of each branch. Functionally this means that when transpiration begins the pressure has to drop more rapidly in the xylem of lower lateral leaves than in those at the top of the tree. It also means that under conditions of water stress peripheral parts of the tree are more vulnerable than the trunk.

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“…In the past, sharp drops had been reported in the hydraulic conductivity (K h ) of excised stems when pure water was used as perfusion fluid (e.g. Huber & Metz 1958). Zimmermann (1978) found that dilute salt solutions injected into xylem prevented the drop in K h caused by water and hypothesized this effect to be a consequence of the swelling and shrinking of intervessel pit membranes as caused by changes in the osmotic strength of the solution.…”

Section: Introductionmentioning

confidence: 99%

Ion‐mediated increase in the hydraulic conductivity of Laurel stems: role of pits and consequences for the impact of cavitation on water transport

Gascó

Nardini

Gortan

et al. 2006

Plant Cell & Environment

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Über die Bedeutung des Hoftüpfelverschlusses für die axiale Wasserleitfähigkeit von Nadelhölzern

Cited by 23 publications

References 30 publications

Logistics of water and salt transport through the plant: structure and functioning of the xylem

Logistics of water and salt transport through the plant: structure and functioning of the xylem

Hydraulic architecture of some diffuse-porous trees

Ion‐mediated increase in the hydraulic conductivity of Laurel stems: role of pits and consequences for the impact of cavitation on water transport

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