In vitro propagation of Oroxylum indicum Vent. was carried out using cotyledonary node explants. Among the different types of cytokinins used for culture establishment, 6-benzyladenine exhibited the best response with higher concentrations (8.87 µM or above) for inducing multiple shoots. Inclusion of indole-3-acetic acid (2.85 µM) into 6-benzyladenine-supplemented medium triggered a high frequency of response as well as a proliferation of shoots. The best medium for proliferation was Murashige-Skoog (MS) medium with 6-benzyladenine (8.87 µM) and indole-3-acetic acid (2.85 µM). However, incorporation of gibberellic acid (1.44 µM) was mandatory to enhance shoot elongation. Repeated subculturing of cotyledonary node and in vitro developed nodal segments in MS medium with 6-benzyladenine (4.44 µM) at 4-week intervals resulted in continuous mass multiplication of shoots without any evidence of decline. Root induction was best (91.6%) when MS strength was reduced to one-quarter and combined with α-naphthalene acetic acid (2.69 µM) and indole-3-acetic acid (5.71 µM), with a high survival rate (70-72%) of plantlets hardened in either soil rite or soil : sand : soil rite (1 : 1 : 2).

Biotechnology has offered a nonconventional method of plant propagation and has been intensively applied as a conservation strategy for sustaining biodiversity for rare plants. In vitro conservation through micropropagation of Ochreinauclea missionis, a rare, endemic and medicinal tree species of Western Ghats in Karnataka region of India is reported. Multiple shoots were initiated from nodal explants on Murashige and Skoog (MS) medium supplemented with 8.8 mM 6-benzylaminopurine (BA) and 0.3% (w/v) activated charcoal. Shoots were elongated in MS medium with a combination of 2.2 mM BA and 5.3 mM a-naphthaleneacetic acid (NAA) or growth regulator-free medium. Individual shoots with a minimum of one node were excised and rooted in vitro on MS medium with 0.3% activated charcoal or ex vitro rooted by treatment with 49 mM indole-3-butyric acid (IBA) for 30 min. Regenerants acclimated in Soil-rite exhibited 65% survival in the greenhouse.