Author : Mi Chan Mon

Summary : The genus Dendranthema (Family: Asteraceae) is a popular cut flower or pot plant species of high economic value cultivated around the world. The genus has more than 100 species of annuals and perennial herbs and shrubs used as floral crops as well as tea and source of other products such as pyrethrum. In vitro propagation using meristems, shoot tips etc. have been successfully applied as a means of large-scale production system for disease-free plants. The present study is carried out in two parts: in vitro propagation and mutation induction with the objectives of developing a protocol for an in vitro method of propagation using ray florets and creation of variations in Dendranthema grandiflora Tzvelev by combining the techniques of in vitro culture and radiation-induced mutagenesis. In developing protocol for rapid propagation, in vitro culture was established by using ray florets on two types of basal media, such as Murashige and Skoog (MS) and Gambong (B5) media, containing various levels of 6-benzylaminopurine (BAP) (0, 0.5,1.0 and 2.0 mg/L) and alpha-naphthaleneacetic acid (NAA) (0, 0.2, 0.5, 1.0 and 2.0 mg/L). In this study the highest percentage of callus formation was observed after 8 weeks on MS medium supplemented with 2.0 mg/L BAP and 1.0 mg/L NAA. However, the highest number of shoot multiplication was obtained from MS basal medium containing 2.0 mg/L BAP and 1.0 mg/L NAA. No growth responses were obserevd on MS and B5 basal media with BAP alone, whereas some roots developed on NAA alone in both types of basal media. After 10 weeks of culture many explants turned brown and died in the B5 basal medium. The highest callus proliferation in terms of fresh and dry weight as established on MS basal media containing 2.0 mg/L BAP and 1.0 mg/L NAA followed by treatment with 2.0 mg/L BAP with 1.0 and 2.0 mg/L NAA after 20 weeks of culture.