Evidence for Air-Seeding: Watching the Formation of Embolism in Conifer Xylem

Journal of Plant Hydraulics ◽

10.20870/jph.2014.e004 ◽

2014 ◽

Vol 1 ◽

pp. e004 ◽

Cited By ~ 5

Author(s):

Stefan Mayr ◽

B. Kartusch ◽

S. Kikuta

Keyword(s):

Water Transport ◽

Juniperus Virginiana ◽

Water Potentials ◽

Ultrasonic Activity ◽

Water Columns ◽

Ultrasonic Emission ◽

Complex Movement

Water transport in plants is based on a metastable system as the xylem “works” at negative water potentials (ψ). At critically low ψ, water columns can break and cause embolism. According to the air-seeding hypothesis, this occurs by air entry via the pits. We studied the formation of embolism in dehydrating xylem sections of Juniperus virginiana (Cupressaceae), which were monitored microscopically and via ultrasonic emission analyses. After replacement of water by air in outer tracheid layers, a complex movement of air-water menisci into tracheids was found. With decreasing ψ, pits started to aspirate and the speed of menisci movements increased. In one experiment, an air-seeding event could be detected at a pit. The onset of ultrasonic activity was observed when pits started to close, and ultrasonic emission ceased at intense dehydration. Experiments clearly indicated that predictions of the air-seeding hypothesis are correct: At low ψ, pit mechanisms to prevent air entry failed and air spread into tracheids. ψ fluctuations caused complex movements of air-water menisci and pits, and at low ψ, air-seeding caused ultrasonic emissions. Main insights are presented in a video.

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Hydraulic constraints and stomatal optimization

10.5194/egusphere-egu21-3435 ◽

2021 ◽

Author(s):

Thomas Buckley

Keyword(s):

Stomatal Conductance ◽

Analytical Solution ◽

Water Transport ◽

Water Loss ◽

Total Carbon ◽

Carbon Gain ◽

Total Water ◽

Water Potentials ◽

Hydraulic Vulnerability ◽

Alternative Approaches

<p>The classical Cowan-Farquhar approach to identifying optimal stomatal conductance treats total water loss as an imposed constraint. That approach can conflict, both physically and economically, with biophysical constraints on water transport. In this talk, I will illustrate these conflicts and discuss alternative approaches -- recently pioneered by Sperry, Wolf, Eller, and their colleagues -- that aim to penalize excessive transpiration by explicitly incorporating hydraulic risk, using hydraulic vulnerability curves (VCs). In this context, I will present preliminary efforts to determine whether VCs accurately reflect the actual probabilistic risk posed by low water potentials (that is, the expected reduction in total carbon gain), as well as an extension to the recent analytical solution by Eller et al.</p>

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Water transport mechanisms for salt-rejecting membranes driven by soil-water potentials

Journal of Membrane Science ◽

10.1016/j.memsci.2018.05.041 ◽

2018 ◽

Vol 563 ◽

pp. 107-114 ◽

Cited By ~ 3

Author(s):

Coleman J. Henry ◽

Jonathan A. Brant ◽

Thijs J. Kelleners

Keyword(s):

Soil Water ◽

Water Transport ◽

Transport Mechanisms ◽

Water Potentials

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Techniques for preparing the Lolium perenne coleorhiza for scanning electron microscope evaluation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100124239 ◽

1992 ◽

Vol 50 (1) ◽

pp. 766-767

Author(s):

Susan B.G. Debaene ◽

John S. Gardner ◽

Phil S. Allen

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Lolium Perenne ◽

Morphological Study ◽

Root Hairs ◽

Inner Pressure ◽

Water Potentials ◽

Radicle Emergence ◽

Standard Fixation ◽

Scanning Electron

The coleorhiza is a nonvascular sheath that encloses the embryonic radicle in Poaceae, and is generally the first tissue to emerge during germination. Delicate hairlike extensions develop from some coleorhiza cells prior to radicle emergence. Similar to root hairs, coleorhiza hairs are extremely sensitive to desiccation and are damaged by exposure to negative water potentials. The coleorhiza of Lolium perenne is somewhat spherical when first visible, after which a knob forms at a right angle to the caryopsis due to inner pressure from the elongating radicle. This knob increases in length until the radicle finally punctures the coleorhiza. Standard fixation procedures cause severe desiccation of coleorhiza cells and hairs, making morphological study of the coleorhiza difficult. This study was conducted to determine a more successful process for coleorhiza preservation.

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Water Transport in Plants under Climatic Stress

10.1017/cbo9780511753305 ◽

1993 ◽

Cited By ~ 6

Keyword(s):

Water Transport ◽

Climatic Stress

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Comparison of the performance of oscillating water column devices based on arrangements of water columns

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.3.2020.10.0555 ◽

2020 ◽

Vol 14 (3) ◽

pp. 7082-7093

Author(s):

Jahirwan Ut Jasron ◽

Sudjito Soeparmani ◽

Lilis Yuliati ◽

Djarot B. Darmadi

Keyword(s):

Wave Propagation ◽

Water Column ◽

Water Depth ◽

Graphical Form ◽

Wave Power ◽

Oscillating Water Column ◽

Power Absorption ◽

Water Columns ◽

Single Column ◽

Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

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