Effect of photoperiod, auxin, and cytokinin on the multiplication rate and growth of amaryllis (Hippeastrum johnsonii) bulbs in vitro.

摘要

Amaryllis (Hippeastrum johnsonii) is a bulbous plant and has a high potential for breeding programs. Since conventional propagation of Amaryllis by bulb offsets is slow, in vitro culture might be developed to overcome this deficiency. The present study describes the effects of photoperiod (16/8, 14/10, and 12/12 h light/dark), different concentrations of NAA (0, 1, 2, and 4 mg l-1) and 2iP (0, 14, 16, and 18 mg l-1) on micropropagation of Hippeastrum johnsonii using bulblets cultured on MS basal medium. For optimal micropropagation by bulblets explants MS medium supplemented with 16 mg l-1 2iP+4 mg l-1 NAA was most effective. Maximum bulblets diameter (6.70 mm), leaf length (14.90 cm), root length (3.31 cm), longest root (4.86 cm), root number (4.00), fresh weight (8.00 g), and dry weight (4.30 g) were obtained on this medium. In most cases, minimum of these traits were observed on medium without NAA and 2iP (control). The least root length (0.23 cm) was recorded in medium containing the highest concentration of 2iP (18 mg l-1). Also, in most cases, 16/8 h light/dark was more effective on Amaryllis micropropagation.