Abstract
Paclobutrazol is one of the most important triazolic compounds which are used as growth retardants in some crops. In this study, the effect of application methods and concentration of Paclobutrazol on plant height of tuberose and possibility of pot production was investigated. In the first experiment, tuberose bulbs were soaked in 0, 25, 50, 75 and 100 mg.l-1 paclobutrazol for 10, 20 and 30 minutes and then planted in pot. The experiment was conducted using a factorial experiment in completely randomized block design with 4 replications. In the second experiment, plants (20 cm hight and fully expanded leaf) were sprayed with 0, 15, 30, 45, 60 and 75 mg.l-1 Paclobutrazol using completely randomized design with 5 replications. In each experiment, the control treatment consisted of untreated bulbs. Results indicated that the tallest plants (54.54 and 60.40 cm in soaking and spray experiment respectively) were control plants. The earliest flowering (107.3 days after planting) also was seen in control plants whereas flowering was delayed to 122.2 days using 100 mg.l-1 paclobutrazol. Shoot length, rachis length and floret number were affected by concentration of paclobutrazol using in preplant bulb soak and spray methods. Our results showed that paclobutrazol could control plant size in relation to pot size.

Keywords: Polianthes tuberose L., Paclobutrazol, Application method