Abstract
The plants were grown at a constant 25°C (18h photoperiod) for 0, 15, 30, 45, 60, 75, 90, 105, 120, and 135 days from May 10 when the plants started the spring flush. Then they were transferred to a constant 18°C (18h photoperiod). There were no differences in the flower-bud forma-tions among the treatments. The flowering percentages were larger with the over 90 days 25°C treatments. In the other experiments, the plants were grown at a constant 18°C (18h photoperiod) from May 10 and then they were transferred to a constant 25°C (18h photoperiod) on May 24, June 9, June 24, and July 9. Then the plants were returned to a constant 18°C (18h photoperiod) after the 25°C treatments for 15, 30, 45, and 60 days. It was necessary for them to be placed a constant at 25°C (18h photoperiod) from early July to early August in order to open many of the flower buds without abscissions. The flowering percentages had large positive relationships with the developments of stamens and pistils, and they were most developed when the plants were placed at a constant 25°C from July 9 to August 23. The plants grown at a constant 10°C from May 10 were formed no flower buds, and 87.1% of terminal (leaf) buds sprouted (lammas shoots). Under the constant temperature conditions at 10, 18, and 25°C, lammas shoots were observed at the leaf buds which formed no flower buds.
