イオンビームの再照射によって秋輪ギク‘神馬’の複数形質を改良した新品種‘神馬2’の育成

‘Jimba’ is the most popular white-flower chrysanthemum cultivar in Japan. However, this cultivar has many lateral buds, and this results in delayed flowering under a low temperature. We have succeeded in the introduction of two new cultivars of chrysanthemum with reduced axillary buds named ‘Aladdin’ and ‘Imagine’ using ion beam irradiation. However, the flowering in these two cultivars was still suppressed under a low temperature. Therefore the objectives of this study were to develop an effective method for obtaining further mutations with ion beam irradiation to develop non-chimeric chrysanthemum mutants possessing excellent flowering and cultivation properties. Many mutants were selected in M1 plants derived from the ion beam re-irradiation of ‘Aladdin’ and B02-1-1. These mutants showed favorable flower characteristics similar to the original ‘Jimba’ cultivar. Further, we succeeded in the introduction of a new cultivar from ‘Aladdin’, named ‘Aladdin 2’, in which both desirable characteristics, few axillary buds and early flowering at a low temperature, were combined. These two traits will contribute to labor and/or energy saving. Furthermore, this novel approach facilitated the mutation-linked induction of genetic changes in other plants, and is being termed ‘Ion Beam Breeding’.