ISHS Acta Horticulturae 813: VI International Symposium on New Floricultural Crops
OPTIMUM IRRADIATION DOSAGE OF UNROOTED DRACAENA CUTTINGS FOR MUTATION |
| Authors: | E.S. Teng, K.W. Leonhardt |
| Keywords: | gamma rays, LD50, Cesium-137, D. deremensis 'Santa Rosa', D. fragrans 'Massangeana', D. fragrans 'Victoriae', D. ×masseffiana |
| Abstract:
Mutation induction using irradiation is a useful method for creating new varieties of ornamental plants that are vegetatively propagated. Dracaenas are an important foliage plant not only in the United States, but also worldwide, and new varieties are needed to maintain consumer demand. The LD50 dosage at which 50% of the plant material survives is generally accepted as the optimum irradiation dosage for the purpose of creating new varieties because an acceptable number of cuttings survive while a large number of mutations are obtained. Unrooted cuttings of four Dracaena varieties were irradiated using Cesium-137 gamma rays at seven different dosages to determine the LD50 dosage. D. deremensis ‘Santa Rosa’, D. fragrans ‘Massangeana’, D. fragrans ‘Victoriae’, and D. ×masseffiana were irradiated at 0, 5, 10, 20, 30, 40, or 50 Gy. Data were collected on root and shoot formation and observations on changes in morphology and variegation were recorded. The LD50 dosages for rooting were estimated as 14.6, 13.8, 5.7, and 17.7 Gy for D. deremensis ‘Santa Rosa’, D. fragrans ‘Massangeana’, D. fragrans ‘Victoriae’, and D. ×masseffiana, respectively. The LD50 dosages for shoot formation were estimated as 19.4, 16.6, 22.1, and 10.9 Gy for D. deremensis ‘Santa Rosa’, D. fragrans ‘Massangeana’, D. fragrans ‘Victoriae’, and D. ×masseffiana, respectively. Visually detectable mutations for each treatment were observed at rates of 0% to 93.3% with chlorophyll mutations being the most common. It is concluded that irradiation of Dracaena cuttings is a useful and practical breeding method and large numbers of cuttings can now be irradiated at the LD50 levels determined in this experiment to attempt to create new varieties of Dracaena for the industry. | |
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