In vitro and ex vitro rooting and plantlet acclimatization in Nerium oleander

Oleander (Nerium oleander L.) is cultivated recently as a flowering pot plant and therefore abundant propagation plant material for commercial use is of great importance. In this study an effort was undertaken to investigate microcutting rooting in vitro and ex vitro and also acclimatization of young microplants. A single white flower clone of oleander was used for the experiments. Microshoots derived from in vitro stock cultures were used as microcuttings and placed for rooting in vitro or ex vitro. For in vitro rooting, the microcuttings were placed in WPM supplemented with IAA or NAA in various concentrations (0, 0.5, 1 or 2 muM). The best rooting was achieved with 2 muM NAA (23%). For ex vitro rooting, the microcuttings were first dipped in various concentrations (0, 0.13, 0.25 or 0.5 g l(-1)) of K-IBA and then were planted in perlite and kept in a fog system with relative humidity adjusted to 96-99%. Rooting was up to 70% with 0.5 g l(-1) K-IBA. After rooting in vitro or ex vitro, the young plantlets were transplanted in pots and placed for hardening in a fog system with initial relative humidity at 95%, which then was decreased gradually to 80% in two weeks. The plantlets in the fog system were either under direct sunlight or under 50% shading provided by a net which lasted for 1 week and was removed afterwards. The transplanting losses for those rooted in vitro for both treatments were less than 5%, whereas no losses were noticed in those plantlets derived from ex vitro rooting.