IN VITRO CULTURE OF SHOOT TIPS OF PELARGONIUM SPECIES

1973 the Swiss Federal Research Station started to produce geraniums which were free of Xanthomonas pelargonii by in vitro cultures.
Up till now 14 out of 20 varieties could be grown by tissue culture methods (Pelargonium zonale, P. peltatum and P. zonalex P. peltatum). The following medias were used: Medium 1, macro-and minor-elements by Murashige and Skoog (1962) except iron, which was added as NaFeEDTA 20 ppm, vitamins by Linsmeier and Skoog (1965), 0.1 % caseinhydrolisate, 3% sucrose, 1.0 ppm Indolyl-butyric-acid (IBA) and 0.2 ppm 6-Benzyl- aminopurine (BA). pH was adjusted at 5.6 to 5.8. For medium 2 BA was replaced by Zeatin and in medium 3, Zeatin was added at a concentration of 1.0 ppm, whereas all other compounds remained unchanged.

Shoot tips (1.0 to 1.5 mm long) of most varieties grew well on medium 1 and 2 and could be planted into Jiffy-seven pots after 2 to 6 months.
Some varieties had to be cultured for three to four weeks on medium 3 and than transplanted to medium 2.

Varieties of P. zonale responded differently to the medias used.
In contrast all varieties of P. peltatum produced significantly more callus in a medium containing IBA only, compared to the complet medium.
Shoot-and leaf formation was strongly reduced.

All cuttings were examined for Xanthomonas pelargonii by the fluorescence test after Lemattre (1970) and by plating out homogenized sections onto calcium agar plates.
All cuttings were found to be free of X. pelargonii.

Symposium on Tissue Culture for Horticultural Purposes

R. Theiler

https://doi.org/10.17660/ActaHortic.1977.78.51