Abstract
Using aseptic plantlets obtained from stem node explants of hybrid red miniature rose (Rosa hybrida cv. Fairy Dance),
the effects of shoot physiological status, medium ingredients, and culture thermoperiod on in vitro flowering were
evaluated. Shoot height, subculture media for shoot multiplication, sucrose concentration, plant growth regulators
(PGRs), mineral substances in media, and thermoperiod had a significant effect on the percentage of in vitro flowering.
Shoots 3 ± 0.2 or 2 ± 0.2 cm in height cultured on Murashige and Skoog (MS) medium containing 2.0 mg dm-3
6-benzyladenine (BA), 0.2 mg dm-3 α-naphthaleneacetic acid (NAA), and 20 g dm-3 sucrose were more suitable for
in vitro flowering than shoots 4 ± 0.2, or 5 ± 0.2 cm in height. The most suitable sucrose concentration for in vitro
flowering was 50 g dm-3 and the most suitable PGRs were a combination of 3.0 mg dm-3 BA and 0.1 mg dm-3 NAA.
Increasing the potassium nitrate to ammonium nitrate ratio or increasing the phosphate concentration in MS medium
had a positive effect on in vitro flowering. The percentage of in vitro flowering was significantly higher at day/night
temperature of 28/20 °C than at other constant temperatures. The percentage of in vitro flowering shoots reached
68.33 % despite the occurrence of abnormal flowers and some unique developmental patterns. It makes miniature rose a
potentially new in vitro experimental platform for research on the molecular mechanisms of flowering ornamental
plants.
Additional key words: abnormal flower, auxins, cytokinins, minerals, Rosa hybrida, thermoperiod.