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- Author or Editor: Chien-Young Chu x
Methods for static liquid culture are described to improve the growth of Doritaenopsis (commercially known as Phalaenopsis) seedlings in vitro. The results showed that seeds not only germinated, but also grew faster in liquid medium. No hyperhydric seedlings were observed in liquid culture when liquid level was accurately controlled by culture density, medium volume, and sealing materials. Although the germination percent was unaffected by medium phase (liquid or solid), sowing density, medium volume, or sealing material, the growth of seedlings decreased as density increased or medium volume decreased. Seeds of 1.5 mg mixed with 20 mL of liquid medium per 9-cm petri dish sealed with two layers of parafilm prompted optimal results. Shoot growth also was enhanced while 75-day-old seedlings were subcultured in liquid media with or without support. Seedling growth was enhanced by adding 20 mL liquid media to 36 seedlings without support after 45 days of culture. It was expected that by static liquid culture, the period from sowing to ex vitro would be 1.5 months shorter than the traditional solid culture.
Experiments were conducted on 6-month-old chinese ixora (Ixora chinensis Lam.) from February 1999 to April 2000. Floral development was studied with scanning electron microscopy (SEM) to determine the flowering sequences. Morphological characters were used to clarify the stages of flowering processes. The time of organogenesis and flowering arrangement was established through field observations. Floral evocation occurred in early September, floral initiation occurred in the middle of September and floral differentiation began in late September. A distinctly convex apex with bracts around the shoulder indicated the beginning of reproductive development. Subsequently, primary inflorescence axes were observed and differentiated into secondary, tertiary, and quaternary inflorescence axes consecutively in about one and a half months. Once the terminal apex reached the inflorescence bud stage, it would flower without abortion, and this may be assessed as no return. The sepals, petals, stamens, and pistil were well developed thereafter and anthesis was achieved in January through March in the following year. The observation of floral differentiation sequences and investigation of floret arrangement made it certain that chinese ixora had cymose inflorescence (cyme), but not corymb. A quadratic equation was established to predict floret number from the differentiation level (a quantitative description of differentiation stage) of a developed inflorescence.