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This study was conducted to elucidate conditions for shoot primordium culture in onion. Shoot tip of onion including 1-2 leaf primordia were cultured on liquid BDS medium containing both auxins and cytokinins under continuous lighting of 2,000 to 8,000 lux on vertically rotating gyration drum with speed of 2 cyclings/min. Induction of shoot primordium was greately dependent on the kind and concentration of growth regulators added in BDS basal medium. The best induction was obtained in combination of 0.5 ㎎/L picloram or 1.0 ㎎/L 2,4-D with 1.0 ㎎/L BA. When NAA was added instead of picloram or 2,4-D, shoot primordia were not induced. Optimal sucrose concentration and pH in BDS medium for shoot primordia induction was 30 g/L and 5.8, respectively. The light intensity appeared to intluence the efficiency of shoot primordia induction with 8,000 lux being the best. Gelrite (0.2%) seemed to be a better gelling agent than agar (0.6%) in the differentiation medium. It seemed that the shoot primordia culture did not cause any observable phenotypic changes in onion.
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