Direct somatic embryogenesis in a selected tea clone, `TRI-2025' (Camellia sinensis (L.) O. Kuntze) from nodal explants

An efficient method for the in vitro propagation of a tea (Camellia sinensis (L) O. Kuntze) clone, `TRI-2025', from somatic embryos is described. This technique involves two phases; the induction of adventitious buds from nodal cuttings followed by the development of somatic embryos. Single nodal cuttings were excised from 1-year-old in vitro axenic cultures and inoculated on MS medium with different combinations of IBA/BAP/GA₃. Induction of multiple shoots from nodal explants occurred on MS medium with 0.5 mg l^–1 BAP, 0.1 mg l^–1 IBA and 0.0 mg l^–1 GA₃ within 6 weeks of incubation. The cultures with multiple shoots were transferred to fresh medium, incubated for 120 days and transferred to MS medium with half-strength macro nutrients, full-strength micronutrients and vitamins and no growth regulator. The direct induction of somatic embryos without callus formation occurred on this medium at 60% frequency within 4 weeks. The production of embryos continued upon transfer of the cultures to fresh medium and a four- to eightfold multiplication rate was obtained during each 6-week culture cycle. The plantlets from these embryos were acclimatised with a 90% success rate. All plants were vigorous and hardy, with well-developed tap-root systems. Received: 20 July 1996 / Revision received: 2 January 1998 / Accepted: 19 January 1998