　　　　　　　　　　　池上秀利＊・巣山拓郎・國武利浩・黒柳直彦¹⁾・松野孝敏・平島敬太・　　　　　　　　　　谷川孝弘・坂井康弘²⁾・長谷純宏³⁾・田中淳³⁾・中原隆夫

　キクの主要品種‘神馬’の開花性及び側枝数等の形質を改良するため，本品種の葉片にイオンビームを照射して再生した系統の開花日と側枝数における突然変異の出現頻度について解析した。

　再生系統は，①⁴He²⁺を照射した場合には，開花日の変異幅が拡大し, 開花日の平均値が遅くなること，②¹²C⁵⁺の照射により草丈当りの側枝数の平均値は変化しないが，その変異幅が拡大すること,③¹²C⁵⁺は¹²C⁶⁺よりも側枝数の変異誘発効果が高いことが明らかとなった。

　さらに再生系統の中から,12月出し栽培及び4月出し二度切り栽培における開花日が早く，12月出し栽培での上位葉のボリュームが優れ側枝数がやや少なく,4月出し二度切り栽培での萌芽性と規格揃いが優れる‘JCH1029'を育成した。

[キーワード：イオンビーム照射，育種，キク，神馬，突然変異，葉片]

　Mutation Induction through Ion Beam Irradiations in Chrysanthemum Cultivars, ‘JINBA', and Breeding a New Line, ‘JCH1029' by This Method. IKEGAMI Hidetoshi, Takuro SUYAMA, Toshihiro KUNITAKE, Naohiko KUROYANAGI, Takatoshi MATSUNO, Keita HIRASHIMA, Takahiro TANIGAWA, Yasuhiro SAKAI, Yoshihiro HASE, Atsushi TANAKA and Takao NAKAHARA (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549 Japan) Bull. Fukuoka Agric. Res. Cent. 24:47-52 (2006)

　For the purpose of improving the characteristics of the main chrysanthemum variety 'Jimaba' raised in Fukuoka prefecture, such as for a longer blooming stage and the number of lateral shoots, we analyzed the mutation patterns of several mutant groups regenerated from leaf segments irradiated with ion beams and created a new variety.

Several facts were revealed: (1) ⁴He²⁺ ion irradiation extended the deviations of mutation in the date of flowering (DF) and delayed the DF of the mutation population by about 4 days, (2) ¹²C⁵⁺ ion irradiation didn't cause changes in the average number of lateral shoots, but enhanced the deviations attributable to mutation in lateral shoot development.

　From the mutant regenerants, we selected one line, 'JCH1029' which displayed three preferable traits: early stable blooming in December and April harvesting, bigger upper leaves and less number of lateral shoots in December harvesting and better budding in cutting-back cultivation and product uniformity in April harvesting. 'JCH1029' attained better performances in these respects compared to 'JINBA' or 'JINBA-2'.