Morphological Characterization and In Vitro Callus Induction in Ashoka [Saraca asoca (Roxb.) De Wilde.]-A Vulnerable Medicinal Tree

A series of experiments were carried out to establish in vitro cultures from explants taken from the field gene bank after surface sterilization of five different genotypes collected from Tamil Nadu and Kerala. These genotypes were studied for morphological characterisation. All parts of tree viz., flowers, bark and seed have medicinal property. The tree is cross pollinated species. Leaves are paripinnately compound. Inflorescence is a corymb. Corolla is gamopetalous with four petals. Fully matured pods are black in colour which contains 4–8 seeds. Callus induction studies were attempted using eleven explants viz., meristematic shoot tip, nodal segment, internodal segment, leaf bits, axillary bud, cotyledon, embryo, seed, anther, ovary and hypocotyl from five different genotypes in three different media viz., MS medium, B5 medium and WPM medium with 2, 4-D at different concentrations-l (0.5 to 4.0 mg l). Genotype 4 collected from Periyakulam, explant-l ovary and the treatment 4 (MS+2, 4-D 2.0 mg l) responded best for callus induction. For in vitro culture of Ashoka species, indirect organogenesis i.e., through the callus induction was found to be the best.