This studies were performed to establish for year-round clonal multiplication in vitro of Cordyline terminalis var. aichiaka Hort. and Scindapsus aureus ENGL. through shoot tips and axilliary buds culture. Authors are more emphasized on the contamination per cent of explant as influenced by culture methods of stock plants and disinfestants, organogenic manipulation by several substances added to the medium and culture environment, and rooting of tissue cultured plants under in vivo condition.
1. For reculturable shoot multiplication, shoot tips and axilliary buds were employable as explants of Scindapsus, only shoot tips of the terminal growth were satisfactory for Cordyline. Contamination per cent of explants was higher in axilliary buds or cross-sections of the stem bearing nodal tissues than actively growing shoot tips, and mostly contaminated by bacteria. In order to reduce contamination of explants, it was necessary to pretreatment of stock plants and to sterilize explants in INCYTE^(tm) solution.
2. Cordyline and Scindapsus yielded substantially more shoots in Gelrite-gelled medium whereas shoot elongation was consistantly better in stationary liquid with filter-paper supports. For rapid multiplication of shoots, addenda to the Murashige-Skoog basal medium were as follows(in ㎎/ℓ): Cordyline=1.0 IAA, 3.0 kinetin, 100.0 adenine sulfate and 150.0 NaH₂PO₄·H₂O. Scindapsus=10.0 kinetin, 150.0 adenine sulfate and 150 NaH₂PO₄·H₂O.
3. An intensity of 3, 000 lux was optimum for the multiplication of shoots and subsequent growth in reculture of Scindapsus. Cordyline showed maximum shoot increase under a light intensity of 500 to 1,500 lux. For rapid shoot multiplication, reculturing of shoot subdivisions was recommended every 6 weeks.
4. Morphological deviations were observed in regenerated shoots or plantlets, especially in Scindapsus. The separation of the chimera components was observed in some cultures, resulting in albino or green shoots.
5. Rooting of regenerated plantlets was promoted by in vivo treatment of IBA, with effective levels of 2㎎/ℓ for Scindapsus and 3㎎/ℓ for Cordyline. In Cordyline, rooting of shootlets was enhanced by increasing plant height, and 84% rooting could be obtained if the shoots were longer than 3.0㎝.
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