Abstract
To clarify the juvenility of bunching onion (Allium fistulosum L.), showing a green plant vernalization, we investigated the effects of the size and age of seedlings on flower-bud initiation. The relationship between flower-bud initiation and the plant size or cumulative leaf number was determined sequentially using young seedlings of ‘Kincho’, ‘Asagi-kujo’, ‘Cho-etsu’, and ‘Kinryo’ sown in a open field on October 1 and October 22. The leaf growth and cumulative leaf number in all cultivars increased over time, but had a suspended inflection period during the winter growing season, which nearly corresponded to the time of flower-bud initiation. In that period, for example, the cumulative leaf number was approximately 5 in ‘Kincho’ irrespective of the sowing time. It is suggested that the cumulative leaf number is a suitable index of the growth stage of the juvenile phase in flower initiation of bunching onion.
