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PROPAGATION OF PELARGONIUM VARIETIES BY STEM-TIP CULTURE
Since tissue culture of Pelargonium is time consuming and expensive, the method was simplified by using only one medium which induced differentiation of shoots and roots.
Therefore stem-tips (1.0 – 1.5 mm) were cultivated on different media in order to find out the best one for cultivation.
Development of leaves and roots was observed by using differently modified agar media after Murashige and Skoog (1962).
Medium 1 was a slightly modified basal medium of Murashige and Skoog, containing two addenda, arginine (2.0 mg/1) and tyrosine (2.0 mg/1). Kinetin (10.0 mg/1), naphthalene acetic acid (0.1 mg/1) and indole acetic acid (2.0 mg/1) were added in order to induce growth of shoots and roots.
Medium 2 was based on that used by Murashige and Skoog and slightly modified by Paludan (1970). It differed from the revised medium of Murashige and Skoog by the addenda NaH2PO4.H2O (170.0 mg/1), adenine (50.0 mg/1), gibberellic acid (1.0 mg/1) and the levels of indole acetic acid (2.0 mg/1) and kinetin (2.0 mg/1). Furthermore, medium 2 was used as basal medium adding higher levels of NH4NO3 (1 650.0 – 4 573.5 mg/1) and kinetin (2.0 – 8.0 mg/1).
The percentage of plantlets of P. zonale (22 varieties) and P. zonale x peltatum (1 variety) produced on medium 1 ranged from 0.0 to 22.7 and on medium 2 from 0.0 to 18.2 respectively.
Generally in the beginning callus and later some leaves and roots developed within 4 to 7 months depending on the variety.
Stem-tips of 4 varieties of P. peltatum only developed large callus tissue without producing shoots and roots.
For experiments with P. grandiflorum (19 varieties) only medium 2 was used.
Callus and shoots developed within 4 weeks.
Most shoots were rooted after a period of 8 weeks.
The percentage of plantlets obtained by this method varied from 0.0 to 54.7, depending on the variety.
The development of shoot and root growth of P. zonale ‘Stadt Bern’ was promoted by a relatively high level of NH4NO3, while it was inhibited by increasing amounts of kinetin (more than 6.0 mg/1).