lectranthus ecklonii (Lamiaceae) is a soft, erect and fast growing shrub that can reach up to three metres in height, thus making it difficult to grow as a potted flowering plant. Therefore, different rates (0, 2, 4, 8 and 16mg a.i. plant-1) of a growth retardant Paclobutrazol were tested for retarding vegetative growth of P. ecklonii for use as a flowering potted plant. To determine the appropriate rate of paclobutrazol, ten replicates of uniform-sized rooted cuttings were applied paclobutrazol as a weekly foliar spray of Cultar® (250gL-1paclobutrazol a.i) for 8 weeks. The plants were grown in a continuous flow hydroponic system within a polyethylene-covered greenhouse with an average daily temperate of 23°C. Paclobutrazol significantly (P≤0.001) retarded stem height, root length, stem dry mass, root dry mass and compactness (estimated from crown diameter and height).The lowest concentration of 2 mg a.i. plant-1 is recommended as it led to two-fold lower root and shoot dry matter, shorter and compact stems. Moreover, the treated plants displayed darker leaves than the untreated.
Keywords: Cultar®, Lamiaceae, Plectranthus, ornamentals, hydroponics