Effect of light condition, sucrose concentration and position of twin scale on ‎maternal bulb on the propagation of twin scale explants of amaryllis (Hippeastrum × ‎johnsonii) under in vitro condition

Amaryllis is one of the ornamental bulbous plants that its proliferation is commercially slow. Application of tissue culture techniques can be a suitable way to increase the propagation rate of this ornamental plant. This study was conducted in two separate experiments. In the first experiment, the effect of light condition and position of twin scales in the mother bulb was evaluated on the regeneration of Amaryllis twin scales. In the second experiment, the effects of different concentrations of sucrose (30, 60 and 90 g/l) and the position of twin scales in the mother bulb investigated. MS medium containing 0.5 mg/l BA+0.1 mg/l NAA was used. Experiments were carried out in a factorial arrangement with five replications in a completely randomized design. Results showed that 16-hour light condition lead to production of more bulblets than dark condition. In terms of bulblet diameter, the brightness conditions were superior to the dark condition. The findings of this study showed the superiority of the outermost twin scales compared to innermost twin scales. Bulblets regenerated from twin scale group 1 were thicker than the other treatments and their dry weight was also higher. Application of sucrose at a concentration of 60 g /l to the culture medium resulted in the production of bulblets with the highest dry weight. By increasing the concentration of sucrose from 60 to 90 g/ l, there was a significant decrease in the regenerated bulblet diameter. Generally, application of medium containing 60 g/l sucrose, twin scales group 1 and 16-hour light conditions is recommended to increase the multiplication rate of Amaryllis.