Abstract
This study was carried out to clarify the effects of cooling treatments of seed-bulbs and day-length during the growing period on the bulb formation in garlic plants.
1. The garlic plants without cooling treatments of seed-bulbs failed to form bulbs under 8 to 16-hour day-length conditions, while plants in the lot of 20 to 30-day or more cooling in the range of 5 to 15°C, developed the bulbs after planting.
2. As in Fig. 1-2, it was recognized that seed-bulbs receiving cooling treatments at temperatures of 5 to 15°C caused their physiological conditions favourable for bulb formation, and the lower the temperature and the longer the period of the treatment, the more significant was the effect, within a certain range.
3. The bulb formation was promoted by long day-length, that is, the longer the day-length becomes, the more hastened the bulbing is. When the garlic plants were grown under 20-hour or more day-length conditions, even if seed-bulbs were not exposed to the cool temperature, the plants formed the bulbs.
4. From these it was recognized that combined effects of cooling treatments for the seed-bulbs and long-day conditions for growing period on bulb formation was additive.
5. Based on the results mentioned above, we discussed the favourable methods of cooling treatments of seed-bulbs to increase the yield of bulbs in the forcing culture.
