Tulip cultivar response to Flurprimidol preplant bulb soaks

Abstract: Flurprimidol preplant bulb soaks (10 to 40 mg L^-1) were applied to tulip (Tulipa sp. L.) bulbs for growth control. Three tulip cultivars ('Page Polka', 'Prominence' and 'Red Present') were used to determine if the efficacy of flurprimidol varied by cultivar. Flurprimidol was compared to paclobutrazol (50 and 100 mg L^-1) and uniconazole (10 and 20 mg L^-1). Flurprimidol preplant bulb soaks significantly (P < 0.05) controlled tulip plant height during the greenhouse forcing when applied to 'Page Polka' and 'Prominence' at concentrations > 15 mg L^-1 and > 10 mg L^-1, respectively. A concentration of 40 mg L^-1 was needed to control plant height during the postharvest evaluation for 'Page Polka' while concentrations > 15 mg L^-1 controlled postharvest plant height for 'Prominence'. No control during forcing or postharvest was provided by any concentration tested on 'Red Present'. The differences observed indicate that the efficacy of flurprimidol as a preplant bulb soak varied with cultivars. In order to determine optimal cultivar doses, growers will need to conduct their own tulip cultivar trials, with flurprimidol concentrations ranging between 10 and 40 mg L^-1.