Summary
Approximately 200 peppermint plants were treated under field conditions five times
during their three–month maturation period with foliar sprays of gibberellic acid
solutions (50 p.p.m.). The young plants evinced measurable response after three days;
there is, however, no indication of earlier flower formation.
The following statistically significant differences were established with respect
to the treated plants:
An increase in cauline length of 33.5 % was noted.
Their fresh weight was 23.2 % lower.
The average size of the leaves was 23.9 % smaller.
A slightly reduced number of foliar glandular hairs per mm2 was noted.
Histological sections showed that the leaves of treated plants were thinner and had
much larger vascular bundles.
Stems had three times as broad a xylem region and the cell walls of the ribs were
much thicker.
The cell walls of morphological sections retained Delafield's Hematoxylin stain to
a much lesser degree.
A 28 % higher concentration of total chlorophyll was found.
No difference in water content or percentage of dry matter was ascertained.
. The yield of volatile oil was 52.4 % lower.
. The oils did not differ significantly in content of total menthol as determined
by microassay and confirmed by ultraviolet spectrophotometric and gas Chromatographie
analyses, the results of which for peppermint oil are described for the first time.
. A comparison of intermediary metabolism by means of paper chromatography revealed
no qualitative differences with respect to carbohydrates, Krebs' cycle acids, and
amino acids.
. A higher concentration of glucose and sucrose was established.
. A possible mechanism of action of gibberellic acid is discussed.
the basis of this work as well as on unpublished work on spearmint, castor bean, anise,
fennel, coriander, and sesame, it might be concluded that gibberellic acid is of doubtful
value in drug plant cultivation.
Zusammenfassung
200 Pflanzen von Mentha piperita wurden während einer 3 monatigen Wachstumsperiode 5 mal mit 0,005 %iger Gibberellinsäure
behandelt. Eine Wirkung ließ sich bereits 3 Tage nach der Spritzung der jungen Pflanzen
erkennen. Folgende statistisch gesicherten Beobachtungen wurden an den behandelten
Pflanzen gemacht:
Der Stengel ist um 33,5 % verlängert.
Das Frischgewicht ist um 23,2 % niedriger.
Die Blätter sind im Mittel um 23,9 % kleiner.
Die Anzahl der öldrüsen pro Fläche ist nur ein wenig verringert.
Die Blätter sind dünner, besitzen jedoch stärkere Leitbündel.
Das Xylem der Stengel ist mehr als 3 mal so stark ausgebildet.
Die Zellwände werden durch Hämatoxylin schwächer gefärbt.
Der Chlorophyllgehalt ist um 28 % höher.
Im Wassergehalt ist kein Unterschied vorhanden.
. Der Gehalt an ätherischem öl ist um 52,4 % geringer.
. Der Mentholgehalt des ätherischen Öls ist nicht signifikant verschieden.
. Es wurden keine qualitativen Unterschiede bezüglich Kohlenhydraten, Krebs–Zyklus
und Aminosäuren festgestellt.
. Es ließen sich höhere Konzentrationen an Glucose und Sucrose nachweisen.
