Abstract
Belonging to one of begonia leaf plants is Begonia rex cultorum, this group belong to the class of rex begonians. An ornamental plant species are known for the leaf colour and pattern. The objective of research to study growth and quality of Begonia rex-cultorum ’Marmaduke’ caused by application of paclobutrazol and shading levels. This experiment was arranged in Split Plot Design consisted of two factors with shading as main plot and paclobutrazol concentration as subplot. The mainplot consisted of three levels, ie., light shading; moderate shading; and heavy shading. The second factor was concentrations of paclobutrazol application consisted of four levels, i.e., without paclobutrazol, 1 ppm paclobutrazol, 2 ppm paclobutrazol and 3 ppm paclobutrazol. The experiment consisted of 12 treatments units with three replications. The result of this experiment showed that there was significant interaction between levels of shading and paclobutrazol concentrations on average leaf area. Application of 3 ppm paclobutrazol with heavy shading gave the lowest average leaf area, whereas non paclobutrazol treatment with heavy shading gave highest average leaf area on 12 weeks after treatment. Treatment of light shading decreased specific leaf area compared with heavy shading. However treatment of 3 ppm paclobutrazol decreased plant height, plant canopy diameter, petiole length, petiole diameter, and specific leaf area, but it increased number of bud tips and number of leaves compared without application of paclobutrazol. Treatment of paclobutrazol (1 ppm, 2 ppm and 3 ppm) on all of shading levels (light, moderate, and heavy) gave higher consumers preference of shoot structure and leaf color compared with non treatment of paclobutrazol on all of shading levels.