Journal of the Japanese Society for Horticultural Science
Online ISSN : 1880-358X
Print ISSN : 0013-7626
ISSN-L : 0013-7626
Studies on the photoperiodic requirement for bulb formation of Japanese varieties of onion, with special reference to their ecological differentiation
S. ABEH. KATSUMATAH. NAGAYOSHI
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JOURNAL FREE ACCESS

1955 Volume 24 Issue 1 Pages 6-16

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Abstract

1. Some experiments were carried out to know the photoperiod requirement for bulb formation of principal Japanese varieties of onions, in the seasons .of 1948-49 and 1951-52.
2. The minimum day length for bulb formation of each variety was determined as follows. 11.5 hours: Aichi-Shiro (Probably derived from Blanc Hatif de Paris).
12 hours: Kaizuka-Wase (Early strain, derived from Senshuki).
12.5 hours: Kaizuka-Wase (Late strain). Aichi-Kiwase (Similar to Kaizuka-Wase).
13 hours: Senshuki (Early and intermediate strains, believed as offsprings of Yellow Danvers Flat). Kisakigake(Derived from Express Globe).
13 hours: Senshuki (Intermediate and late strain). Ninomiya-Maru(Improved from Senshuki), Yamaguchi-Koda ka (Improved from Sapp-oroki).
14.25? hours: Sapporoki (Derived from Yellow Globe Danvers).
3. There was close relationship between earliness or lateness of bulb formation and minimum day length requirement for bulbing among many varie-ties, and the types requiring shorter photoperiod were earlier and the longer types later.
4. The regional adaptability of the onion varieties tends to be determined by the photoperiod also in Japan. The variety Sapporoki which requires long-est photoperiod in Japan has been grown only in Hokkaido, and the shorter day varieties Aichi Shiro and Kaizuka Wase in mild zones. The distribution of the main variety Senshuki tends to be inconsist-ent, but its early strain is adapted to the southern part of Japan and the late strain to the middle and northern part.
5. The bulb formation is not begun under deficient day length and the thickening of bulb tends to be controlled under excessive day length owing to its rapid maturity, thus a variety demonstrates its abi-lity best, where the minimum temperature and photoperiod for the bulb formation visit at the same time.
6. It may be concluded from the temperature and photoperiod of onion growing regions of this country, that the varieties of 12 hours are adapted best to the Loochoo Archipelago, the 12.5 hours to the middlesouth parts of Kyushu and Shikoku, the 13 hours to the middlesouth part of Honshu and the greater parts of Kyushu and Shikoku, the 13.5 hours to the middle and north part of Honshu, and probably the 14.25 hours to Hokkaido as well as to highlands (over 1400m above the sea) of the middle north part of Honshu.
7. All the varieties tested were not pure concer-ning the genes that determine the minimum photo-period for bulbing. It is very interesting from the standpoint of the evoluton of variety, that varying process of Senshuki (13_??_13.5 hours) to Kaizuka-Wase(12 hours) can be explained from this fact.

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