1995 Volume 64 Issue 3 Pages 589-598
Changes in abscisic acid (ABA) content and water status in bulbs of Allium wakegi were investigated throughout the year. The life cycle of A. wakegi was divided into a nonbulbing period (from October 1 to March 15), a bulb developing period (from April 1 to May 15) and an established bulb period (from June 1 to September 15) ; it was divided in a dormant period (from April 1 to August 15) and an active growth period (from September 1 to March 15)
ABA content in bulbs increased during the bulb developing period and then tended to decrease during the established bulb period. In the non-bulbing period ABA content was relatively low. Water potential decreased in the bulb developing period, was remained low during the established bulb period and then rapidly increased just after planting. Pressure potential in bulbs tended to be higher in the non-bulbing period than in the established bulb period. The innermost scales had the highest ABA content. during the different stages of bulb development.
During the non-bulbing and bulb developing period, there was a significant inverse correlation between ABA content and pressure potential in bulbs. This is interpreted that the changes in water status is associated with an increased ABA content during the bulb developing period; however, the correlation was poor during the established bulb period. During the dormant period, there was a positive correlation between ABA content and the depth of dormancy although the time of deepest dormancy (May 1) did not coincide with the maximum ABA content (June 1). From these results, it is suggested that bulb development is accompanied by a change of water status which induces accumulation of ABA and that ABA is involved in bulb dormancy.