Studies on the forcing of Aster Savatieri MAK. var. hort. MAK. IX.
A. ISHIDA · Journal of the Japanese Society for Horticultural Science · 1966
This study was carried out to examine the growth and flowering of Aster Savatieri MAK. var. hort. MAK. as affected by the temperature and the daylength given prior to the low temperature and gibberellin treatments, and also by various regulators sprayed before and after flower initiation.1. The growth and flowering were accelerated when the plants had been grown at 10°C for 3 weeks prior to the low temperature treatment, but the plants grown at 15°C for 3 weeks were not sufficiently accelerated. The plants grown at 20° and 25°C for 3 weeks showed no budding. No distinct influence of the day-length on the growth and flowering was noted.2. The commercial shipping of cut flowers before the middle of December will be possible when the plants are grown under the following program: 3 weeks at 10°C from the middle of September to early October for accelerating flower initiation, 4 weeks under 1°-2°C from the middle of October to early November for breaking rosette, then 3-time applications of 40ppm of gibberellin at 2-week intervals from early November to early December.3. Applications of 10 and 50ppm of NAA, 50 and 100ppm of TIBA, 50 and 100ppm of RNA accelerated the flower formation even if the plants were under an unfavorable temperature for flower initiation, but the effect of the concentration and the number of times of applications of those chemicals on the flower formation was not obvious. 50 ppm of gibberellin application, on the other hand, showed a marked effect on stem elongation, but no effect on flower initiation.4. 10 and 50ppm of NAA, 10, 000 and 50, 000 ppm of ethylen-chlorohydrin, and 50 and 100ppm of kinetin applications to the plants which had already initiated flower primordia and which were under an unfavorable temperature for breaking rosette, could not break the rosette, but the plants flowered in rosette form.Six applications of 50ppm of gibberellin after flower initiation, however, could break the rosette and accelerated the flowering.5. There was a close relationship between flower initiation and stem elongation. Consequently, gibberellin and low temperature treatments for the plants before flower initiation could not break the rosette. Though the gibberellin applications temporarily promoted the internode elongation, the plants formed the rosette leaves again on the top soon after a series of the applications. Gibberellin and low temperature treatments could break the rosette only when applied after flower initiation.