Micropropagation of Rhododendron caucasicum L. (Ericaceae) via shoot bud cultures

This thesis was designed to determine the most effective medium and thereby an effective micropropagation protocol for the production of Rhododendron caucasicum via shoots cultures. The lateral buds of mother plants which were previously brought from Georgia were employed as explants. During shoot proliferation experiments, Anderson's Rhododendron medium (AN) was used as basal medium. Various plant growth regulators (PGRs) as well as their concentrations were employed in the course of shoot formation trials and zeatin (0.5 mg/L) was found to be the most effective PGR tested. In shoot multiplication experiments, AN basal medium was then supplemented with stable zeatin and variable PGRs, e.g. IAA, NAA, IBA, each being applied with various concentrations (2.0, 4.0 and 8.0 mg/L) . At the end of six or eight week culturing period where photoperiod applications were also available as, 16/8, the most suitable combinations for shoot multiplication were found to be zeatin/IAA. The highest shoot height (8 cm) was observed from the basal medium supplemented with zeatin (0.5 mg/mL) and IAA (8 mg/mL), whilst zeatin (0.5 mg/L) and IBA (4.0 mg/mL) combination was found to be more effective in terms of leaf formation. Nevertheless, all IBA concentrations tested (0.5, 1.0, 2.0, 4.0, 8.0 mg/L) were ineffective in terms of root formation and elongation for R. caucasicum. Again, none of those tested basal media supplemented with IBA (10 mg/L), those being semi-solidified as well as containing active carbon (AC) (0.01%) or without AC was proved to be effective in the root formation on the plantlets of R. caucasicum. During shoot multiplication stage, root formation was established from only one plantlet which was grown on the medium containing NAA (2.0 mg/L), it was then transferred to subculturing medium and as a result root formation could not be sustained from this sibling anymore.