Studies on the Light Controlling Flower Initiation of Pharbitis Nil. X
アサガオの花芽形成を支配する光条件について X

Atsushi TAKIMOTO, Yoshiyuki NAITO
1962 Shokubutsugaku Zasshi  
Pharbitis seedling is one of the most sensitive short-day plants, and a single long dark period is sufficient to induce the maximum flowering response. Seedlings grown under continuous illumination for 1-2 days are induced to flower when subjected to a 16-hour dark period, but those germinated in darkness and kept in darkness for 2-4 days followed by continuous illumination cannot initiate flower buds. That is, a light period is necessary before a dark period of sufficient duration can induce
more » ... owering. Generally, in short-day plants, a high-intensity light period must precede a dark period of sufficient durations to induce flowerings,1o,13) . The process proceeding during this period is often called "the high-intensity light process ". Liverman and Bonner8> considered that the high-intensity light process is a photosynthetic one, supplying the energy required for the following dark process. But the so-called high-intensity light process is probably not required only for the supply of energy. Meijer12) investigated the spectral dependence of the main light period reaction in Salvia occidentalis, a short-day plant. In Salvia, blue and far-red are effective for flower inhibition (long-day effect) and red is not so effective. Similar spectral dependence was observed in many long-day plants, Brassica, Hyoscyamus, etc.15,1s, 19>. Stroun et al.17~ grew Perilla nankinensis under various coloured lights (long-day condition) from germination for 56 days and then subjected the plants to 10 short days under various coloured lights. The plants grown under green light initiated flower buds readily, independently of the light quality during the short-day treatments. Among the plants grown under white, blue and red light, the plants subjected to short days under the green light did not initiate flower buds, but those subjected to short days under white, blue and red light did so. In the present investigation, Pharbitis seedlings were grown under various light conditions from the start of germination; 2 days later (only in Experiment 1, 1-4 days later), the seedlings were subjected to a 16-hour dark period (only in Experiment 2, 824-hour dark periods), and the flowering responses were examined. Material and Methods The material used was seedling of Pharbitis Nil Chois., strain Violet. To obtain uniform germination, the seeds were treated with conc. H2SO4 for 20-30 minutes, washed thoroughly in running water for about one day, and spread on moistened sand. Two days after the treatment with H2SO4, germinating seeds were selected for uniformity and sown in 18 cm diameter clay pots containing garden soil so that each pot contained 19 plants. They were then placed under various light conditions at 25-30°C. The seedlings emerged one day later. Two more days later (in Experiment
doi:10.15281/jplantres1887.75.255 fatcat:gbsjoxr7dnfgpohmuqcl7hushq