In vitro mutation on chrysanthemums

Mutation breeding is one of the methods which is most used for ornamental plant breeding. Chrysanthemum is the genus that has the richest mutant cultivars in ornamental plants. In this study white 'Bacardi' was irradiated by gamma radiation. The objective of this study was to create variation by gamma irradiation and improving traits by mutation breeding. In order to determine effective mutation dose (EMD-LD₅₀), in vitro cuttings were irradiated with gamma (⁶⁰Co) source at 7 different doses. After irradiation all plants were sub-cultured. At 60 days of regeneration shoot and root lengths were measured. The EMD was calculated by linear regression as 20 Gray, comparing control shoot length to irradiated groups (50% reducing length of control). For creating main population, 3000 in vitro plantlets were irradiated with EMD. In vitro subcultures were continued till M₁V₄ period. Some changes were observed at leaves and flowers of the plants such as; variable flowers, flowering time, differentiation on plant length, chimeric leaves, flower number per bunch and ray floret differentiation. The changes of the ray florets were; pink colour, pink strips and length changes. Approximately 8.5-21% of useful mutant lines were selected from the population.