a b s t r a c t
The effects of different media, temperatures and plant growth regulators on the ex vitro propagation of
twin-scale cuttings as well as on the relationship between starch degradation and bulblet development
of Hippeastrum vittatum cv. ‘Red lion’ were studied. Sawdust was the most optimal medium for the
propagation of twin-scale cuttings resulting in the lowest percentage of rotting scales and the best quality
bulblets. Furthermore, 25 ◦C was a more suitable temperature than 30 or 20 ◦C. Gibberellic acid (GA3),
indole-3-butyric acid (IBA) or 1-naphthyleneacetic acid (NAA) did not result in scale propagation and
bulblet development. In particular, NAA treatment significantly increased the frequency of rotten scales.
During bulblet formation and development, starch content in the mother scales declined earlier and
more rapidly, especially in the outer scale of twin scales. The culture of scales at 30 ◦C resulted in a
distinct increase in the consumption of starch in the scale. The starch content in bulblets increased
during development. Starch accumulation in bulblets at 25 ◦C was most remarkable at the last stage of
development. The dominant soluble sugars in the bulbs of H. vittatum were fructose, sucrose and glucose,
fructose content being highest in the mother scales. However, the key soluble sugar in the bulblets was
sucrose and its content increased linearly over the first 50 days.