Growth Regulation of New Clones of Rotheca myricoides 'Uganden- sis' (syn. Clerodendrum ugandense)

The occurrence of position effects, i.e. topophysis, was tested for two new clones (29 and 112) of Rotheca myricoides (Hochst.) Steane & Mabb. ‘Ugandensis’ (syn. Clerodendrum ugandense Prain). The position from which cuttings are taken from of the mother plant can affect the later vegetative and generative development of the plants, e.g. partly reduce their extensive longitudinal growth. Three different kinds of cuttings were used during propagation in two sets of experiments: tip cuttings of vegetative branches, stem cuttings of vegetative branches and stem cuttings of generative branches. Their height, branching and flowering development was assessed in periodic intervals over a period of four months. Compared to 112, clone 29 displayed a significantly reduced longitudinal growth and a significantly better rate of branching was displayed. Furthermore, the results for the vegetative tip cuttings of both clones showed a significant decrease in height (6–10 cm) compared to the stem cuttings from vegetative branches combined with an increase in branching (1–2.5 branches) compared to both other types of cuttings. Apart from choosing the appropriate clone, using vegetative tip cuttings can therefore be a partly effective method to reduce the extensive height and improve the branching during commercial production of Rotheca myricoides ‘Ugandensis’. With regard to flowering, no significant differences between the two clones and the three types of cuttings were found in the statistical analysis.