やぐら性ネギ類

Viviparous onions are cultivated mainly by home gardeners in the northern parts of Japan, China, the United States, and Europe. In spite of an abundance of common names applied to those viviparous onions, there is not any one cultivar name attached to them, and there also prevails a no less confusion in the systematic knowledge of those forms. Cytogenetic studies have been carried out with 12 strains of viviparous onions cultivated in Japan. From the result obtained, those 12 strains could be classified into 3 different groups as shown in the following: 1. Six (Yagura-negi group) strains showing the same karyotype as that of Allium fistulosum, excepting 2 strains which are heterozygote to a deficient satellite. The following formulae were assigned to these 2 different strains; K(2n)＝14V+2J^T and K(2n)＝14V+J+J^T. 2. One (bulb-bearing onion group) strain showing the same karyotype as that of Allium cepa. The formula assigned to this strain was K(2n)＝14V+2J^t. 3. Five (Catawissa onion group) strains showing clearly the same heterozygous karyotype. The following formula assigned to these strains was K(2n)＝14V+J_1+J^T_2. All the strains belonging to Catawissa onion group have revealed usually the irregular meiosis in PMCs, while the other ones mentioned above showed, in turn, the normal meiotic processes. At meiotic metaphase-I of their PMCs Catawissa strains showed the configulation, (8－3)_II+(0－10)_I, the average frequency of pairings being 6.19_II+3.18_I. Thus the later meiotic processes showed certain irregularities, providing several lagging chromosomes and certain chromosome bridges. Abnormal sporad cells, accompanying micronuclei, resulted usually. In consequence, most of young pollen-grains thus raised became to be degenerated soon. The comparative analyses of karyological, ecological and morphological features with the Catawissa onion will be duly taken as a certain hybrid form derived from the crosses between Allium cepa and. A. fistulosum, both of which are provided with genes for the character viviparity. A number of informations obtained from various literatures concerning the origin of Catawissa onion made the hypothesis quite feasible that this onion would have been raised through certain hybridization process, spontaneous or artificial, in some northern region of the United States during the years between 1700's and 1800's. In consequence, the proposed classification with viviparous onions will be presented as follows: 1. Yagura-negi; Allium fistulosum L. var. viviparum Makino 2. Bulb-bearing onion, Egyptian onion, or tree onion; Allium cepa L. var. bulbellifera Bailey 3. Catawissa onion or top onion; Allium cepa L. var. viviparum (Metzg.) Alef. (Allium aobanum Araki)