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Nodal explants from hop were exposed to plant growth regulators to determine suitable media for initiation from axillary buds and subsequent micropropagation. Efficient culture establishment (96.6% of explants) was achieved on Murashige and Skoog (MS) medium (modified to contain 1 mg l 2l thiamine hydrochloride) supplemented with 0.57 mM indoleacetic acid (IAA) and 2.22 mM 6-benzylaminopurine (BA). Subsequent transfer of explants to treatments containing an auxin ([1-naphthaleneacetic acid] NAA or IAA) and BA, 6-[g,g-dimethylallylamino]purine (2iP), kinetin (KIN) or thidiazuron (N-phenyl-N H -1,2,3-thidiazol-5-ylurea [TDZ]) resulted in significantly different amounts of multiplication. Optimal TDZ-supplemented media elicited a greater than threefold increase in the number of shoots and nodes generated per explant compared to optimal media containing BA, 2iP and KIN. Shoots were successfully rooted using half-strength MS supplemented with 5.71 mM IAA and 4.9 mM indolebutyric acid (IBA), and regenerated plants were successfully transferred to soil. An overall micropropagation schedule, which can be implemented into hop commercialization programs, includes: (i) establishment in MS with 0.57 mM IAA and 2.22 mM BA; (ii) multiplication in MS with 0.57 mM IAA and 2.27 mM TDZ; (iii) elongation in MS; and (iv) rooting in half-strength MS with 5.71 mM IAA and 4.9 mM IBA.

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Mature embryos of Costus speciosus were excised and cultured on Schenk and Hildebrandt's (1972) nutrient medium containing auxins and cytokinins either alone or in combination. Multiple shoots were obtained when kinetin and indole-3-butyric acid were supplemented each at 0.1 mg 1(-1) concentration. Embryo-derived plantlets were multiplied through propagation of rhizomes and the propagules derived from a single embryo were designated as an embryoclone. Twenty such embryo-clones were maintained in the field. Variations in rhizome biomass yield and diosgenin contents of these embryoclones were noted. Thirty-six percent of the embryo-clones studied were high diosgenin yielding types. Diosgenin contents at the intraclonal level were uniform. The in vitro raised plants were morphologically uniform and indistinguishable from their parent.