2017 Volume 43 Issue 2 Pages 370-374
To establish a proposal for a guiding principle supporting appropriate management of Iris pseudacorus L., which had been used as an important vegetation bank species until the Invasive Alien Species Act, this study investigated propagation characteristics of rhizome cut pieces in spring and examined their growth after top cutting. When the fresh weight of the rhizome cut pieces in the spring became greater than 15 g, the individual plant flowering rate increased gradually. Individuals of more than 30 g achieved a flowering rate higher than 76％. The flowering rate was highest for individual plants that had two green leaves, but it became progressively lower for increasing numbers of green leaves: non-flowering individuals grew better than flowering individuals. In the 0 cm height scape-cutting treatment, no significant difference was found in the numbers of flowers and fruits the next year. In the 5 cm height top-cutting treatment, the flowers and fruits in the next year were significantly fewer. From the results described above, we proposed planting individuals with heavy fresh weight in spring and a few green leaves, to create a beautiful sight immediately. Moreover, we showed a guiding principle for management that uses a method of top-cutting after flowering for reduce seed dispersal.
