INDUCTION OF FLOWER MUTATION COMPARING WITH CHRONIC AND ACUTE GAMMA IRRADIATION USING TISSUE CULTURE TECHNIQUES IN CHRYSANTHEMUM MORIFOLIUM RAMAT

1. The combined methods of irradiation and culture yielded a mutation rate 10 times higher than the conventional chronic cutting method and also produced non chimeric mutants.
2. Since the only culture method for unirradiated plants provided few and scarce mutations using any source of explants, irradiation is vital for effective mutation induction.
3. In the combined irradiation and culture methods, the flower color mutation rate was the highest in regenerators from petals, followed by those from buds and leaves.
4. In the combined irradiation and culture methods, chronic irradiation yielded a significantly higher flower color mutation rate and a wider color spectrum on the regenerators than those obtained through acute irradiation.
5. Selection of a mutated colored petal as the explant under chronic irradiation should promote the induction of a wider color spectrum on the regenerators.
6. In acute irradiation onto cultured materials, damage to the regenerated lines increased as the dose increased; therefore, the proper irradiation method should be chosen according to the breeding purpose.
7. The six flower color mutant varieties registered were derived from chronic irradiation.

The combined method of chronic irradiation with floral organ cultures proved conclusively to be of great practical use in the mutation breeding of flower species, and enlarging the mutation spectrum in vegetatively propagated plants.

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