Interactive effects of plant growth regulators and explants on direct shoot regeneration of Viola odorata

The aim of the study was to develop a protocol for in vitro shoot regeneration based on a solid Murashige and Skoog (MS) basal medium supplemented with various concentrations of plant growth regulators (PGRs) like Indole-3-butyric acid (IBA), kinetin (KIN) or benzylaminopurine (BAP) using leaf, petiole, root, and crown disk segments of a valuable medicinal plant Viola odorata. The best percentage of direct shoot regeneration (67.50%) and the maximum number of micro-shoots (9.50) were obtained with crown explants on MS medium containing IBA (0.5 mgA l!1) combined with BAP (3 or 4 mg A l!1). The best elongation (5.25 cm) of micro-shoots was observed in crown explants on a medium containing 1 mg A l!1 gibberellic acid (GA3) followed by GA3 at 0.5 mg A l!1 and similar explants. Irrespective of the concentrations of GA3, the minimum length of shoots was observed in leaf explants. A half-strength MS medium containing activated charcoal and supplemented with 1.5 mg A l!1 IBA resulted in the best rooting (78%) of elongated shoots. All acclimatized plantlets survived and showed a normal growth. The study reports a simple and applicable protocol for micropropagation of V. odorata through direct organogenesis.