Growth regulator effects on plant height of potted Mussaenda 'Queen Sirikit'.

摘要

Mussaenda, a tropical ornamental shrub developed in the Philippines, was examined as a potential potted floriculture crop in the USA because of its showy white, picotee (white with pink margins), pink or red sepals, and fragrant yellow flowers. However, the profuse upright growth habit of some Mussaenda cultivars is undesirable for pot plant culture. The growth regulators daminozide (as B-Nine), ancymidol (as A-Rest) and paclobutrazol (as Bonzi) were applied at 2 commercially recommended rates, andusing 2 application methods (spray or drench), to Mussaenda cv. Queen Sirikit plants in 1573-cm3 pots, and their effects on plant height were investigated. The treatments (all concentrations as active ingredients) were daminozide spray (2500 or 5000 mg/litre), ancymidol spray (33 or 66 mg/litre), ancymidol drench (0.25 or 0.50 mg/pot), paclobutrazol spray (25 or 50 mg/litre), and paclobutrazol drench (0.125 or 0.25 mg/pot). In subsequent experiments, the same growth regulators were applied at higher concentrations and in either 2 or 3 applications. The most attractive potted plants were produced with 2 spray applications of 5000 mg daminozide/litre or 2 drench applications of 0.5 mg ancymidol/pot. Higher concentrations or additional applications excessively reduced plant height. Paclobutrazol sprays or drenches at any concentration or method of application number did not control plant height.