Chrysanthemum morifolium is an important temperate cut flower for Malaysian floriculture
industry and the lack of new local owned varieties led to this mutation breeding research. The
objective of this study was to compare the effectiveness of ion beam irradiation in generating
mutations on ray florets and nodal explants of Chrysanthemum morifolium cv. ‘Reagan Red’. Ion
beams has become an efficient physical mutagen for mutation breeding. The ray florets and nodal
explants were irradiated with ion beams at doses 0, 0.5, 1.0, 2.0, 3.0, 5.0, 8.0, 10, 15, 20 and 30 Gy.
The 50% of in vitro shoot regeneration (RD50) for ray florets explants was 2.0 Gy and for nodal
explants was 4.0 Gy. Thus, relative biological effectiveness (RBE) for ray florets was found 2.0
times higher than the nodal explants. The regenerated plantlets were planted in the greenhouse at
MARDI, Cameron Highlands for morphological screening. Overall performance of survival
plantlets derived from in vitro nodal and ray floret explants was recorded. The characters studied
include plant morphology and flowering characteristic. The ray florets explants were found to be
more sensitive to ion beam irradiation and generated more mutations as compared to nodal
explants.