Articles
Article 19
Meristem tip culture which has been used to establish stocks free of certain viruses of some ornamentals has not been used successfully with Pelargonium sp.
The principle problem has been the lack of a suitable medium for Pelargonium shoot and root regeneration from meristematic tips.
Investigations were initiated in our laboratory to develop a medium on which Pelargonium could be successfully cultured.
A modification in the Murashige and Skoog tissue culture medium has worked very successfully for the development of plantlets from Pelargonium meristem tips.
The modified medium contained 2 mg/1 of indolebutyric acid (IBA) or 1 mg/1 of naphthalene acetic acid 0,04 mg/1 kinetin, 2 mg/1 of L-cysteine, 100 mg/1 of M-inositol, 100 mg/1 of coconut milk, and agar (0.4 or 0.9%) at pH 5.5–5.7.
Thirty-five cultivers of P. hortorum, 6 cultivars of P. peltatum L. and 5 seedling lines of P. hortorum were tested on this medium.
P. hortorum cultivars Sincer ty, Blaze, Skylark, Red Perfection, Irene and Madam Languethe readily developed shoots and roots in 10 days.
Snow Mass, Hildegaard, Wirth’s Red, and Blue Blood were difficult to successfully culture, but roots and shoots were produced if the medium contained higher levels of IBA (4–6 mg/1). It was difficult to obtain shoot and root regeneration from cultivars of P. peltatum.
More than 15,000 cultures of Pelargonium have thus far been done with more than 30% successful shoot and root regeneration on all cultivars in all experiments.
Nearly all cultivars of P. hortorum contain one or more viruses.
Thirty-two cultivars were first exposed to thermotherapy (38°C for 4 wk), then cultured from meristem tips.
After transplanting, these cultivars were indexed on Chenopodium quinoa, Vigna sinensis and Cucumis sativus (using 4% PEG in the Pelargonium extract) for viruses reported to be infectious to Pelargonium.
Vegetatively propagated cuttings removed from meristem tip cultured and virus-indexed plants rooted 10% faster than non-meristem tip cultured plants.
Flower performance on plants derived from meristem tip cultured cultivars such as Pink
‘) This work was supported by the Pennsylvania Flower Growers Assoc., the Oglevee Floral Co. and Valentine Girards, Inc.