In Vitro Propagation of Cephalanthera rubra (L.) Rich., an Endangered Orchid, Using 2,4-D, NAA and BA

Orchids are universally popular due to the wide range of colors, sizes, shapes, and scents in their flowers. The demand for orchids as cut flowers and pot plants is increasing in the flower market. Seed germination of orchids is comparatively low in the wild as they typically require fungal symbionts during their germination. Micropropagation of orchids is a major approach to orchid conservation and commercial production. Cephalanthera rubra (L.) Rich., one of Iran’s endangered orchid species, has been cloned using leaf as explant, Murashige and Skoog (MS) as culture medium, and α-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) (both at the concentrations of 0, 0.1, 0.2, 0.3 and 0.4 mg L–1) as well 6-benzyladenine (BA) (at 0, 1, 2, 3 and 4 mg L–1) as plant growth regulators (PGRs). In order to initiate an axenic culture, the disinfection of leaf explants was performed with sodium hypochlorite and mercury chloride. The highest number of shoots (4.33) was obtained in medium enriched with 4 mg L–1 BA. Maximum stem length (4.73 cm), leaf number (5.33) and node number (2.86) was obtained in medium supplemented with 3 mg L–1 BA. The largest number of root (5) and the highest length of root (4.83 cm) was produced on medium augmented with 0.3 mg L–1 NAA. Rooted plantlets were transferred to pots filled with peat and perlite in 1:1 proportion and acclimatized to ambient greenhouse conditions with an average of 90% survival rate. This is the first report on the micropropagation of C. rubra (L.) Rich.