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A method for inducing xylem emboli in situ: experiments with a field-grown tree (1992)

SALLEO, S. ; HINCKLEY, T. M. ; KIKUTA, S. B. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 15 (1992), S. 0

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ISSN: 1365-3040

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: A pressure collar, assembled around 25cm sections of 4-year-old willow twigs, was used to examine cavitation events under field conditions. When the air pressure inside the collar was raised to between 1–8 and 2–8MPa, ultrasound acoustic emission signals were triggered which indicated the breaking of water columns in the xylem. The hydraulic conductivity of the twig portion inside the chamber decreased markedly. As a result, water potentials and conductances in leaves at the end of the twig decreased. Similar changes were induced at comparable pressures in detached twigs. The equipment used is described in detail, and evidence is presented that the mechanism of this artificial production of emboli follows the air-seeding principle hypothesized for natural cavitation events.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01001.x

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Seasonal dynamics of major cations in xylem sap and needles of Norway spruce (Picea abies L. Karst.) in stands with different soil solution chemistry (1988)

Kazda, M. ; Weilgony, P.

Springer

Plant and soil 110 (1988), S. 91-100

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ISSN: 1573-5036

Keywords: calcium ; deficiency ; magnesium ; needles ; nutrition ; nutrient mobilisation ; potassium ; seasonal dynamics ; soil solution ; soil water ; spruce ; xylem sap

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Soil solution, xylem sap and needles of mature trees were sampled in three spruce stands over one vegetation period and analysed for major cations. Investigations of nutrient distribution between these three pools and evaluations of seasonal dynamics give the following results: The highest nutrient concentrations in the xylem sap occur at the time of bud break and become gradually lower during the vegetation period. The trees show similar trends of xylem sap concentrations with time for potassium, calcium and magnesium regardless of the nutritional status of the plots. No coupling of xylem sap to soil solution composition can be observed in spite of a high variability of soil solution chemistry in time. The major cations in the current needles exhibit a significantly different trend with time. No time-based correlations for nutrient contents could be found for the needles from the previous year. Despite mobilisation of storage pools in the deficient stand, trees are not able to increase the Ca and Mg contents in the needles up to the level of the other stands. Potassium could be retranslocated in sufficient extent for nutrition of current needles. Due to seasonal variability and dependence upon internal processes, such as retranslocation and mobilisation of nutrients, xylem sap does not seem to be a good tool for the estimation of the nutritional status of forest sites. It was concluded that only minor transport into new foliage via xylem sap will proceed after nutrient flush during the bud break and the nutrient content in the new biomass will be governed by dilution due to biomass growth or by nutrient transport by other means than xylem sap.