Chiang Mai Journal of Science

         Seven varieties of chrysanthemum leaves explants were cultured on MS media supplemented with 2 mg/L 2,4D and 1 mg/L Kinetin for callus induction and regenerated for shoot initiation in MS media supplemented with 1 mg/L BA and 0.1 mg/L NAA. Healthy in vitro plantlets were irradiated by gamma ray with 6 treatments; 0, 20, 40, 60, 80, and 100 Gy. The survival irradiated in vitro chrysanthemum was selected and keep on cultured until grew completely with shoot and root plantlets. Acclimatization was tested at Doi Khun Wang Agricultural Research Center (Royal Project), Jomthong, Chiang Mai, Thailand. One hundred percent of healthy plantlets which were transferred into natural environment were survived and grown to young plants on nurse tray in greenhouse and then they were transplanted into 4 inches diameter plastic pot as pot plants. After sixteen weeks in greenhouse, chrysanthemum no.D23 and no.D27 had no flower and grew slowly. Mutants were discovered, twenty gray irradiated chrysanthemum no.12-10 showed whole pink shade petal while the parent line was pink-orange shade flower. Chrysanthemum flower no.11-4 showed decrease yellow shade petal compared with pink-orange parent line and no.11-8 showed increase yellow shade petal on the middle of flower compared with pink-yellow parent line. Chrysanthemum no. M07-4 showed flower form mutation which produced numerous petals.