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In vitro Micropropagation of Rhododendron kawakamii Hay.

  • Date of declaration:2020-05-19
Ya-Ling Ho、 Yue-Ken Liao
Year
2020
Key Words
acclimatization, azalea, rooting, shoot proliferation
Abstract

Plant tissue culture techniques were used for the mass propagation of the native Taiwanese azalea, Rhododendron kawakamii Hay., in this study. Apical shoots of 6~8-wk-old in vitro seedlings derived from mature seeds of R. kawakamii were collected as explants for shoot proliferation. Explants, cultured for 24 wk, were incubated in a 1/2 Anderson medium containing 1.07~34.4 6-(γ-γ-dimethylallylamino) purine (2iP) to induce shoots. The highest shoot production (533.8 shoots explant-1) was obtained from medium supplemented with 17.2 μM 2iP. Shoot elongation was enhanced in media containing lower levels of 2iP (4.3~8.6 μM) with 8 wk of culturing. Multiple shoots in clumps obtained from the shoot elongation stage were subcultured as 1 unit without separation in agar medium supplemented with 0~2 μM indole-3-butyric acid (IBA) for root induction. Various types of adventitious roots including short, long and cluster-rooted types were observed in rooting culture. The highest rooting percentages (> 97.5%) were observed in media containing 1~2 μM IBA, among which over 80% were of the long and clustered types of roots. High survival rates (> 95%) were obtained from explants with various types of roots after acclimatization. Plants of 8 cm in height were obtained after 1 yr of cultivation in a greenhouse. In the present study, an in vitro propagation protocol was successfully established using limited seeds for indigenous R. kawakamii which is rare in Taiwan nowadays and difficult to collect in the field.