Studies of in vitro Propagation Systems for Sugar Beet

Commercial cultivars of Beta vulgaris (sugar beet) and an annual diploid line, as well as some breeder's materials developed in Ireland, were used in studies on several in vitro culture procedures. An efficient micropropagation system, based on cytokinin-mediated release of apical dominance in axenic shoot cultures, was established for all genotypes. Callus was initiated by several combinations of naphthalene acetic acid and benzyl aminopurine, and was maintained indefinitely on a defined medium. Shoot regeneration from callus developed from petiole explants was achieved using two different protocols but somatic embryogenesis was not observed. The best frequency of shoot regeneration achieved was 16% of calli responding with 1 to 30 adventitious buds developing on responsive calli. A number of apparently normal, rooted plants were obtained from regenerants. Out of 200 ovaries dissected from flowering spikes of cv. Hilma, two ovules developed into plantlets after a two-step culture procedure