Ca Uptake and Distribution in Rhododendron Selected for Lime Tolerance / Ca-Aufnahme und -Verteilung bei auf Kalktoleranz ausgelesenen Rhododendron

The calcium content and the severity of disease symptoms of 15 Rhododendron clones selected in vitro for Ca tolerance and of three control cultivars were investigated under different Ca regimes. Greenhouse grown plants were exposed to increasing Ca concentrations by supplementary Ca(NO₃)₂ added to t...

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Bibliographic Details
Published in:Gartenbauwissenschaft 1993-05, Vol.58 (3), p.111-116
Main Authors: Mordhorst, A. P., Kullik, C., Preil, W.
Format: Article
Language:English
Subjects:
Acid soils
Calcifuges
Calcium
Greenhouses
Hypochromic anemia
Leaves
Orchard soils
Plant diseases
Plants
Symptoms
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Summary:The calcium content and the severity of disease symptoms of 15 Rhododendron clones selected in vitro for Ca tolerance and of three control cultivars were investigated under different Ca regimes. Greenhouse grown plants were exposed to increasing Ca concentrations by supplementary Ca(NO₃)₂ added to the irrigation water (65, 130, and 195 mg Ca/1). In addition, microcuttings were cultured in vitro on media with 120, 240, 480, and 960 mg Ca/1, given as CaCl₂ or (NO₃)₂. Under greenhouse conditions 7 of the 18 clones tested showed significantly increasing Ca contents with increasing Ca supply in veins of young leaves, grown during the experiment. This phenomenon was neither seen in young leaf blades nor in blades or veins of old leaves developed before Ca exposure started. Chlorosis and necrosis at the borders of leaves appeared in only a few cases and could not be correlated with Ca supply. The Ca content of chlorotic leaves was significantly lower than those of green leaves. The Ca content increased in tissue of microcuttings when the Ca concentration in the medium was increased. Young leaves turned yellow-green on media supplemented with higher concentrations of CaCl₂, but they remained green on Ca(NO₃)₂-containing media. Ca content in leaf tissue and the appearance of disease symptoms under increasing Ca supply appear not to be suitable markers for lime tolerance in Rhododendron, because these parameters did not distinguish between control plants (lime-sensitive) and clones known to be lime-tolerant under field conditions. Furthermore, it could be demonstrated that high Ca supply (in absence of HCO₃⁻) does not suppress growth in Rhododendron. Die Ca-Gehalte und die Ausprägung von Schadsymptomen an Blättern wurden bei 15 in vitro auf Ca-Toleranz ausgelesenen Rhododendron-Klonen und drei Kontrollsorten bestimmt. Die Pflanzen wurden im Gewächshaus durch Anreicherung des Gießwassers mit Ca(NO₃)₂ (65, 130, 195 mg/1 Ca) steigenden Ca-Konzentrationen ausgesetzt. Zusätzlich wurden die Klone als Mikrostecklinge in vitro auf Medien mit 120, 240, 480 und 960 mg/1 Ca (Zugabe als CaCl₂ oder Ca(NO₃)₂ kultiviert. Unter den Testbedingungen des Gewächshauses zeigten Blattadern junger Blätter, die während des Versuches gebildet wurden, bei 7 von 18 untersuchten Klonen signifikant steigende Ca-Gehalte mit steigender Ca-Versorgung. Dieser Tatbestand wurde weder in jungen Blattspreiten noch in alten Blattadern oder -spreiten, die schon vor Versuchsbeginn entwickelt wurden, beoba
ISSN:0016-478X
2364-6047