Interaction of light and temperature in germination of
Nigella, typical light inhibited seeds, was investigated according to variation of presoaking time represented by number of Dp; hours. And the following results were obtained.
1. It was confirmed that germination promoting response to weak light and inhibiting response to strong light, exist individually.
2. Seed's response to weak promotive light at 15°C marked maximum sensitivity at Dp; 18hrs. This is a pure photochemical reaction to weak light (6×10
3 MKS), in which there is a fraction acting more promotively by high temperature after irradiation.
3. No reversible relation between red and far-red was observed in
Nigella's weak-light response, though it was proved by Brothwick in
Lepidium and considered to be a general nature of weak light response.
4. Inhibitive response to long time irradiation, which appears most remarkably at DP; 30hrs meant inhibitory response to far-red radiant energy. This inhibitory effect becomes null at 0°C. Then, this has not been regarded as a mere photochemical raction but a more complicated enzymatic reaction.
5. Response to high temperature also exists separately from light response. It prevented germination strongly in earlier Dp; hrs. But, in Dp; 24-60hrs, comparatively hort time (3-6hrs) exposure to high temperature brought about 10% ncrease of germination rate.
6. The germination rate obtained from simultaneously exposure to light and igh temperature, was equal to a total sum rate of (1) effect of high temperature temperature reaction), (2) inhibited rate of inhibitory response to long time irradiation, nd (3) promoted rate by exposure to weak light (short time radiation) at igh temperature, added to (4) the germination rate in continuous darkness.
7. It has been clarified that each of three factors (weak-light response, strong ight response and temperature response) exists separately from the other two actors.
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