Some factors affecting the in vitro growth of Stevia rebaudiana Bertoni

Gelling agent plays an important role in the in vitro growth of Stevia rebaudiana. Agar solidified MS medium fortified with 1.5 mg/l BA + 0.5 mg/l Kin was found the best concentration for shoot induction from apical meristem and nodal explants, while gelrite solidified MS medium containing the same concentrations of hormones produced weak plants. Healthy and profuse growth of regenerated shoots along with roots were observed when shoots were again subcultered in agar solidified MS medium with 0.1 mg/l IBA, whereas gelrite solidified medium with 0.1 mg/L IBA again produced 1 ]2 average number of shoots and roots. The medium became liquid in case of gelrite medium during the growth period and the pH of the medium was also changed. Gelling effect was further confirmed by transferring the shoots from gelrite solidified medium to agar solidified medium with the same hormones concentration. Shoots resumed normal growth and proliferation after they were transferred to agar medium. This effect may be due to the change in concentration of the cations (Ca, Mg).