Phloroglucinol and Silver Nitrate Enhances Axillary Shoot Proliferation in Nodal Explants of Vitex negundo L. –an Aromatic Medicinal Plant

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A reliable method is described for rapid proliferation of axillary shoots from nodal segment of mature field-grown aromatic and medicinal plant Vitex negundo through in vitro culture. Of different concentrations of N6-benzyladenine (BA) evaluated as supplements to Murahige and Skoog (MS) medium, BA at 1mg/l was effective in enhancing bud break and shoot regeneration. Response of explants was also influenced by explanting seasons. Early bud break and enhancement of shoot regeneration could be achieved by supplementing phloroglucinol (PG) at 100mg/l and silver nitrate (20 mg/l) in addition to BA (1 mg/l). These compounds appear to have synergistic effects on enhancement of high frequency multiple shoot regeneration. The number of shoots obtained in the presence of AgNO3 and PG was significantly higher (15.12±0.33) than other media tested. The efficacy of culture establishment with high percentage of responding explants is depending on seasonal factors in addition to culture conditions.  Among the different concentrations of IBA (0.1, 0.5 and 1.0 mg/l) tested, 0.5mg/l IBA was more effective for inducing roots within two weeks of culture and 85% of the microshoots produced long healthy root system. Ex vitro rooting of micropropagated shoots was achieved by treating the basal end of the microshoots in IBA solution (4000 ppm) followed by planting in plastic pots filled with a mixture of soil, sand and vermicompost (6:2:1). Rooted microshoots were successfully established in the field with 80 percent survival rate after three months.