Bud regeneration from inflorescence explants for rapid propagation of geophytes in vitro

Bulbs, corms and other subterranean storage organs are commonly used as exp lant source material for the establishment of geophytes in vitro. The inflo rescence stalk was found to be a good alternative source of explants to ove rcome explant contamination originating from underground storage organs. In florescence explants of Allium, Dichelostemma, Eucrosia, Gladiolus, Haemant hus, Hyacinthus, Narcissus, Nerine and Ornithogalum were used to establish cultures in vitro. The regeneration potential of the inflorescence was comp ared with regeneration from bulb twin scales or from apical buds isolated f rom corms. Gladiolus (Iridaceae) explants isolated from the floral stem jus t below the expanding florets, still enclosed in the bracts, were highly re generative in the presence of naphthalene acetic acid (NAA) and kinetin. In the presence of 2,4-dichlorophenoxyacetic acid and benzyl aminopurine (BA) in the medium, explants isolated from the tissue at the junction between t he peduncle and the pedicels of a young Nerine (Amaryllidaceae) inflorescen ce regenerated several buds. The scapes of young unemerged inflorescences t aken from sprouting bulbs of Narcissus (Amaryllidaceae), following a 15 deg rees C storage treatment, regenerated buds in the presence of NAA, BA, elev ated phosphate and adenine sulfate in the medium. The number of buds regene rated depended on the location on the scape from which the explant was isol ated, and on the duration of the 15 degrees C treatment. In Allium (Alliace ae), capitulum tissue between the flower pedicels regenerated buds. Explant s excised from the peduncle, as well as the pedicel-peduncle junction of Di chelostemma (Alliaceae), Ornithogalum, Hyacinthus (Hyacinthaceae) and Eucro sia (Amaryllidaceae) regenerated several buds in each type of explant. In t he case of Haemanthus (Amaryllidaceae), pedicel-peduncle junction explants regenerated buds only when excised from inner whorl florets. Propagation pr otocols and the potential use of expediently isolated inflorescence explant s for efficient micropropagation of geophytes are discussed.