1. The Comparisons between the Effects of Photoperiod and Gibb. Treatment : The length of petunia leaves was more increased by Gibb. treatments(25 and 75ppm)than the increase in day length(from 8 to 16 hours), however the width of leaves was increased as the increase in day length but not appeared any response by Gibb. treatments. The first flower open date in petunia was more forced by the increase in day length than Gibb. treatments.
The length and width of snapdragon leaves were increased with the increase in day length, but with Gibb. treatments the width of leaves was rather decreased. The weight of flesh matter and dry matter in snapdragon was not increased by Gibb. treatments but by the increase in day length. The increase in day length showed the forcing effect on the first floret open date of snapdragon, whereas Gibb. treatments showed the retarting effect.
2. Replacing Photoperiodism by Gibb. Treatment: Photoperiodism on the plant height, the length of main shoots, the length of leaves, the first flower open date. and the number of Rowers in petunia could be substituted with Gibb. treatments. The effect on the growth and the flowering by photoperiod could be in general replaced by Gibb. treatments.
In the plant height, the number of basin shoots and the number of nodes in snapdragon, photoperiodism could be nearly substituted by Gibb. treatment. By Gibb. 1965 treatments under short day length, the first flower open date and the spike length in snapdragon showed most retarting effect. Therefor, the forcing and retarting effects by Gibb. treatment were most extrem under short day length.
3. The Mechanism of Interaction between Photoperiod and Gibb. Treatment: In this experiment the mechanism of interaction in petunia could be inferenced by Brian´s(1) hyphothesis, but the mechanism of interaction in snapdragon could not be inferenced by Brian´s(1) hyphothesis. Consequently the Gibb. treatment could substitute only one part of several effects of photoperiodism.
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