In vitro propagation of a precious orchid species, Renanthera Imschootiana Rolfe

Abstract

Renanthera imschootiana Rolfe, an extremely precious and horticultural valuable tropical epiphytic orchid, needs to be conducted in vitro propagation. In this study, we investigate the effect of phytohormones on rapid in vitro propagation of this orchid species. Seed germination is favorable in basal medium MS (Murashige – Skoog, 1962) for 45 days after sowing. Protocorm proliferation is the best in the MS medium supplemented with 1.0 mg/L KIN (Kinetin), 0.5 mg/L NAA (α-naphthaleneacetic acid), 15% CW (coconut water). The MS medium added with 1.5 mg/L KIN and 15% CW is suitable for shoot multiplication from protocorm, with average number of the regenerated shoots per explant up to 15.33 after 12 weeks. The growth of the shoots is the best in the MS medium combined with 2.0 mg/L BA (6-benzylaminopurine), 0.25 mg/L NAA, and 15% CW, with average height of the shoots reaching1.0 cm during 8 weeks. The highest rate of rooting from the shoots, on average 2.4 roots per shoot, is obtained in the MS medium fortified with 1.0 mg/L NAA after 8 weeks. The plantlets are transplanted to substrate mixture of sphagnum moss and peat with ratio of 1:1 adapted to natural greenhouse condition with survival rate of 91.6%.