INFLUENCES OF TEMPERATURE AND SUBCULTURING IN-VITRO ON SUBSEQUENT FLOWERING OF LIMONIUM-SINUATUM MILL

Lateral buds from newer stalks of annual statice (Limonium sinuatum Mi ll. 'Early Blue') were cultured in vitro at 20 degrees C or 27 degrees C on a half strength Murashige-Skoog medium containing 0.01 mg.liter( -1) NAA, 1.0 mg.liter(-1) BA, 30 g.liter(-1) sucrose, and 8 g.liter(-1 ) agar. The emerging shoots were excised from clumps of multiple shoot s and subcultured for 4 weeks at 20 degrees C on a hormone-free rootin g medium. The rooted plantlets were transplanted into pots and grown a t 20 degrees C. The bolting percentage of the plants derived from the primary culture at 20 degrees C was 67%, whereas that of plants kept a t 27 degrees C was only 13%. When divided clumps of multiple shoots we re subcultured twice for multiplication using the same medium as in th e primary culture, plants failed to bolt. However, when comparable sho ots were subjected to 2 degrees C for 4 weeks during the final subcult ure for multiplication or rooting culture, almost all plants bolted. R epeated subculture for multiplication following the low temperature tr eatment resulted in a decrease in the bolting percentage. These result s indicate that high temperature and repeated subculturing during in v itro multiplication cause a disappearance of the flowering potential o f the micropropagated statice plants, whereas low temperature treatmen t during subculture can restore it.