Genotypic differences for induction of bracting in cauliflower with 2-chloroethylphosphonic acid (ethephon)

Summary Bracting (i.e. bracts of the inflorescence growing through the surface of the curd) is a serious problem in commercial growing of cauliflower. Enhancement of bracts was most effective when ethephon was applied to plants that had just initiated a curd. When ethephon was applied 7 to 10 days later the effect diminished again. Ethephon effects were small when the chemical was applied after only a few curds had been initiated. Bracting increased continuously over the range (0 to 960 mg l^-1) of applied concentrations. There was an interaction with temperature during the early curd growth. Higher temperatures increased the effectiveness of ethephon.After an ethephon application significant differences between cultivars were observed in the extent of bracting. For screening cultivar differences in resistance against bracting, an ethephon application (240 mg l^-1) when nearly all plants had initiated a curd, was best.The experiments were carried out when the author was employed at the Research Station for Arable Farming and Production of Field Vegetables (PAGV) in Lelystad, The Netherlands.