Growth, development and colour response of potted Dianthus caryophyllus cv. Mondriaan to paclobutrazol treatment

The ability of paclobutrazol to reduce Mondriaan carnation height, and its effect on leaf and flower colours and other quality characteristics which render it suitable as a flowering potted plant were investigated. A first experiment was conducted during spring in an unheated greenhouse, applying paclobutrazol as a drench (0.45, 0.7, 0.9 and 1.12 mg a.i. per pot) or a spray (0.16, 0.35, 0.51 and 0.65 mg a.i. per pot) to pot-grown plants. A second experiment was conducted during winter, when paclobutrazol was applied as a drench (0.125, 0.25, 0.35 and 0.45 mg a.i. per pot). The results obtained suggested that paclobutrazol could well be used to control the growth of Mondriaan and improve its commercial quality. In spring, drench applications were more effective than spray in reducing plant growth, although the best quality plants were obtained with the 0.51 mg spray application. In winter, the drench of 0.25 mg paclobutrazol per plant produced plants of better quality than the control. Leaf colours darkened slightly with all spray treatments and with substrate drench doses ¿0.45 mg. The red winter-grown control flowers had a more purple colour than those grown in spring, while paclobutrazol accentuated this colour change in winter-grown plants only. © 2002 Elsevier Science B.V. All rights reserved.