Abstract: To screen the effective reagents for promoting the tillering of Ornamental bromeliads, different concentrations of ethephon, paclobutrazol, and 6-BA were used, with water as the control. The tillering-promoting effects were evaluated, and the underlying mechanism was explored. The results showed that 100 ppm ethephon was the most suitable reagent for promoting the tillering of ornamental bromeliads ‘flat-headed red’. Under the concentration of 100 ppm ethephon, the tillering coefficient could reach 10 or above when the fertilization was stopped 30 days before the treatment, and pH of ethephon solution was adjusted to 6 with potassium carbonate. Compared with the control, ethephon treatment increased leaf number and plant height, while had limited effects on leaf length, leaf width, and crown width. Moreover, ethephon treatment promoted C/N ratio in roots, stems and leaves, the chlorophyll content in the later stage, as well as the accumulation of total nitrogen, phosphorus and potassium in plants. The contents of total nitrogen, phosphorus and potassium were positively related to tiller number. These results suggested that the ethephon treatment might promote tillering through increasing C/N ratio and the contents of total nitrogen, phosphorus and potassium in ornamental bromeliads. This work provided technical support for the breeding of ornamental bromeliad seedlings and the possibility of localizing ornamental bromeliad seedlings.

Key words: Ornamental bromeliad, tillering, ethylene, C/N ratio, chlorophyll, nitrogen, phosphorus, potassium