In vitro propagation of Oroxylum indicum Vent. a medicinally important forest tree

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 mu M or above) for inducing multiple shoots. Inclusion of indole-3-acetic acid (2.85 mu M) 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 mu M) and indole-3-acetic acid (2.85 mu M). However, incorporation of gibberellic acid (1.44 mu M) 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 mu M) 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 a-naphthalene acetic acid (2.69 mu M) and indole-3-acetic acid (5.71 mu M), with a high survival rate (70-72%) of plantlets hardened in either soil rite or soil: sand: soil rite (1:1:2).