Induction of mutants in flower color of chrysanthemum (Dendranthema grandiflora   (Ram) Tzvelev) using gamma irradiation

An experiment was carried out at Biotechnology Lab and Post-Graduate School's greenhouse of the Universidad de Oriente, Maturín, Monagas state in order to obtain flower color mutants of chrysanthemum (Dendranthema grandiflora (Ram) Tzvelev) using gamma irradiation. In order to induce flower color mutant, 3-cm long shoots under in vitro culture were irradiated using a 60Co source located at the Instituto Venezolano de InvestigacionesCientíficas, Caracas, Venezuela, with doses of 0.0; 0.5; 1.0; 1.5 and 2.0 Krad. The parameters evaluated were survival percentage, number of leaves/shoot and growth rate at 7, 14, 21 and 28 days after irradiation. Plants were acclimated and later transferred to the greenhouse where the number of daylight hours was reduced in order to induce flowering. Once the flowers were open, color mutants were evaluated. The best survival rate of irradiated explants was achieved with a dose of 1.5 Krad, and the best growth with a dose of 0.5 Krad. The 2.0 Krad dose affected survival, number of leaves/shoot and growth rate. Mutants were obtained at all dose used, with the best results obtained with 1.0 Krad (60 % mutants) and 0.5 Krad (38.88 % mutants). "Copper" color flowers were most frequent