Studies on the shortening the juvenile phase of tulip under the controlled environment. II
On the thermoperiodicity of juvenile tulip
1967 Volume 36 Issue 3 Pages 315-323
Details
1967 Volume 36 Issue 3 Pages 315-323
In the present experiments from the view of autoecology in the juvenile phase of tulip the relation between temperature and growing phase were mainly examined and investigations are to be made with respect to the method for shortening the juvenile phase under the controlled environment.
It was proved that the annual juvenile bulbs conditioned by the treatment with 23°C for 20 days before lifting and with 4°C for 45 days after lifting, the sprouting time at 13°C was retarded and irregular sprouts were observed.
In the case of treatment with high (35°C) and low (4°C) temperature, the sprouting became earlier and the sprouting in uniform was shown. It was concluded that the treatment with high and low temperature is more effective means for promotion of sprouting in comparison with the single treatment of high or low temperature. Accordingly in practice a treatment with high temperature for 20 days and low temperature for 40 days was considered to be sufficient.
Observing from the amount of production of bulbs, it was confirmed that the optimum duration of growth in a phytotron held at 13°C was about 130 days, and thereafter the temperature for growth was raised to about 23°Cso as to induce the bulb into dormancy.
From the results of similar experiments which were carried out on biennial juvenile bulbs, it was found that the biennial bulbs has a thermoperiodicity similar to that the annual bulbs.
The above mentioned results for the long thermoperiodicity in the juvenile phase of tulip were summarized as follows:
20vH+40L+120M+20H
where vH is 35°, L is 4°, M is 13°, and H is 23°C. and number is day of the treatment with definite temperature.
The seedling of tulip reaches to adult phase after 6 years under the natural environment, however, it was shown by the results of part I and II in this experiments, that the juvenile phase would be shortened to about 3.2 years under the controlled environment.
