Effects of temperature, plant growth regulators and substrates and changes in carbohydrate content during bulblet formation by twin scale propagation in Hippeastrum vittatum ‘Red lion’

• Sawdust is the optimal substrate for double-scale propagation of Hippeastrum cv. ‘Red lion’.
• 25 °C was a more suitable temperature than 30 or 20 °C for double-scale propagation.
• GA3, IBA or NAA did not result in scale propagation and bulblet development.
• Starch in mother scales declined earlier and rapidly, especially in outer scales.
• Fructose was highest in mother scales and sucrose was dominant in bulblets.

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.