Abstract
This research was carried out to study the influence of the date of harvest and the curing of harvested bulb on bulb formation and the date of sprouting. Variety Imai-wase was used for this research and plants were harvested at seven times from May 25 to July 25 every ten days.
1. Even after falling of the top, thickening of the bulb continued for 20-30 days and the process of bulb formation finished when the death of the leaf blade occurred.
The bulbs dug out in early stage had less storage leaves than that of late harvest, while there was no effect of harvest time on other parts in bulb.
2. In bulbs planted on late August, the date of sprouting was influenced by the date of their digging: the earlier the date of digging, the earlier sprouting. Accordingly it is considered that the bulbs dug out in its bulbing period enters dormancy, and after a certain period dormancy of bulb is broken; the earlier the date of digging, the earlier the breaking of dormancy.
3. In bulbs stored in room, however, harvesting at an early stage in the bulbing period, except the extremely early harvesting, caused late sprouting because of inhibition of leaf growth after the breaking of dormancy.
4. The curing of harvested bulbs delayed the time of sprouting, while the withering of leaf blade by a desiccant promoted the sprouting of onion bulb.
