Breaking Dormancy in Allium wakegi Araki by Infiltration of Water into Bulblets

Abstract

Dormancy of Allium wakegi Araki is induced in late April or early May under the natural conditions of Japan. The dormancy of bulblets was dramatically broken by forced water infiltration and by removal of foliage scales.
1. Water infiltration under pressures of 25 kPa and 200 kPa for one hour increased fresh weights of bulblets. This treatment shortened the number of days to sprouting 26 and 30 days, respectively, compared to the control bulblets which were dipped in water under normal atmospheric pressure of 100 kPa. A significant negative correlation was found between the amount of water absorbed by the foliage scales and storage leaves and the number of days to sprouting after treatment.
2. Water infiltration by bulblets was accompanied by increased respiratory activities within 3 days of treatment.
3. Breaking of dormancy by leaf removal depended on the number of scales removed. We conclude that dormancy of bulblets of Allium wakegi Araki is regulated by the foliage scales surrounding the apex. We postulate that water infiltration makes the amount of abscisic acid decreased in the foliage scale cells and results in the breaking of dormancy. Scale removal may have sharply decreased abscisic acid content in the same manner as water infiltration.