Variability of Chrysanthemum Cultivars Induced by Gamma Irradiation

Abstract

This study aimed to determine the exposure dose of gamma radiation on stem cuttings of chrysanthemum cultivars. Explants of 11 cultivars (‘Eldora’, ‘Rania’, ‘Aileen’, ‘Olga pink’, ‘Sevda’, ‘Heimish’, ‘Rania’, ‘Attirance’, ‘White Plume’, ‘Coral King’, and ‘Leporem’) were subjected to different levels of gamma irradiation (0, 10, 30, 50, 70, 100, and 150 Gy). The results revealed that variation in vegetative growth parameters, viz., plant height, stem diameter, number of leaves, leaf length, leaf width, total number of flowers, flower diameter, number of petals, petal length and width, and number of buds occurred in the M1V1 generation compared to the control (0 Gy). The survival rates of the gamma-irradiated cultivars changed dramatically. The number of surviving plantlets based on 50% lethal dose (LD50) was found in 100 and 150 Gy treated plants 60 days after radiation. In addition, the highest percentage of plant survival was observed in the control, while the lowest percentage was observed in plants irradiated with 100 Gy and 150 Gy, along with delayed bud initiation and flowering. The number of days from planting to flowering was low in all of the control cultivars, even though the flowering percentage was high in the control compared to the treatments. The highest number of branches was observed in plants that were subjected to 100 and 150 Gy treatment, while 10, 30, and 50 Gy gamma irradiation revealed similar vegetative characteristics to all the control cultivars. Maximum leaf abnormality and leaf color variation were observed in the 70, 100, and 150 Gy treatments. Mutant varieties were produced from those treated with 10, 30, 50, 70, and 150 Gy, in which a higher number of mutants and mutation frequency were found in the 30 and 70 Gy treatments. The results showed that more flower color mutations occurred due to higher exposure to irradiation with minimum alteration in the vegetative growth in all cultivars. These results establish a standard to identify the gamma radiation dose that can induce mutations in chrysanthemum. Additional key words: flower color, growth parameter, lethal dose, mutation frequency, stem cutting, vegetative growth