Effectiveness of ion beam breeding on netted melon 'Earl's favourite' (Cucumis melo L.)

We investigated the growth characteristics at the Msub(2) and Msub(5) generation that were irradiated with an ion beam (sup(12)Csup(5+)) on the netted melon 'Earl' s Favourite kenonfuyu2' (Cucumis melo L.). In the Msub(2) generation, the plant length (about 20 days after it was transplanted) and the bisexual flower parasitism rates decreased; so that the irradiation with an ion beam exerted an influence to decrease growth. Moreover, ion beam irradiation spread the fluctuation band of the weight of fruits, the net, and the sugar degree. We investigated the Msub(5) generation that had the following superior inherited characters (low temperature fruits elongation, high sugar degree, favorable net, and high bisexual flower parasitism rate) at the Msub(2) generation, and it suggested that the Msub(5) generation displayed the fixation inherited characters because the fluctuation band became smaller. Moreover, it was guessed that a useful mutation had been acquired because in contrast with 'kenonfuyu2', a former irradiation variety, growth characteristic differences were found. It was suggested that ion beam was effective in the mutation breeding of the netted melon 'Earl' s Favourite' because a useful characteristic change was admitted.