Gamma Rays and CarbonIon-Beams Irradiation for Mutation ...

similar in both cultivars when the corm shoot tips were cut vertically. In
contrast, ‘Williams’ was affected when the horizontal slicing was applied.
‘Williams’ showed an average of 0.6 g using the horizontal slicing method,
compared to 0.9 g using vertical slicing. Finally, the vertical slicing method
was selected as a better method to regenerate the banana explants, and then
this type of slice was obtained from shoot tips as a material for ion beam
irradiation.
4. 3. 1. 2. Biological effects of the carbon ion-beam irradiation doses
(Gy)
Results of the two cultivars (‘Cavendish Enano’ and ‘Williams’)
used in the first irradiation are described as follow. The analysis of variance
for the height of explant showed significant differences between cultivars
and among ion-beams doses (P≦0.05). As shown in Fig. 36-A and -B, the
weight and height of plantlets were affected when the Gy doses were
increased irrespective of cultivars. Highest growth behavior in terms of
weight and height were observed when doses ≦2 Gy were applied. These
parameters decreased when 4 Gy or higher were used.
The survival rate (%) of the explants is presented in Fig. 36-C.
In this study, it is supposed that the lower doses ≦8 Gy had never
interfered those survival rates even though the greater does resulted the
higher mortality. Hase et al. (2002) reported that the high-linear energy
transfer (LET) radiation such as heavy-ion beams have higher biological
effects than low-LET radiation such as gamma and X-ray, producing a
survival reduction and frequency of aberrant cells increased linearly. Thus,
it is possible that the chromosome aberration induction depended on the
LET. As shown in Fig. 37, the LD50 for both ‘Cavendish Enano’ (A) and
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