Influence of Plant Growth Regulators (PGRs), Antioxidants, HgCl2 and photoperiod on in vitro shoot proliferation of Ashwagandha (Withania somnifera)– a medicinal crop

The present investigation was carried out to see effects of Plant Growth Regulators, antioxidants, HgCl2 and photoperiod on various characters of shoot proliferation viz., period of initiation of shoots, response (%), number of shoots/explant, number of nodes/explant and shoot length (cm) with objectives to optimize conditions of proliferation from nodal explants. Callus induction and indirect regeneration was also studied. MS basal media supplemented with combination of cytokinin and auxin were added viz., (1.0 mg/l BAP + 1.0 mg/l NAA, 1.0 mg/l BAP + 2.0 mg/l NAA, 2 .0 mg/l BAP + 1.0 mg/l NAA and 1 .0 mg/l Kinetin + 1.0 mg/l IAA, 1.0 mg/l Kinetin + 2.0 mg/l IAA, 2 .0 mg/l Kinetin + 1.0 mg/l IAA). Maximum shoots were induced with 2.0 mg/l BAP + 1.0 mg/l NAA, showed highest (85.33%) response of shooting. All the treatment combinations of BAP and NAA were found most responsive as compared to Kinetin and IAA. When activated charcoal (100-300 mg/l) and ascorbic acid (50-150 mg/l) were added in medium supplemented with 2.0 mg/l BAP + 1.0 mg/l NAA. 200 mg/l of activated charcoal and 100 mg/l of ascorbic acid showed highest (80.00% and 80.40%) response of shoot induction. In photoperiod treatment, maximum shoot induction (2.57) was observed in 16:8 hours with (100%) response with minimum days shooting and maximum number of shoot regeneration (3.71) from callus with highest morphogenesis response. Maximum contamination control (89.14%) along with maximum shoot induction (3.86) was observed when explant was sterilized with 0.1% HgCl2 for 3 minutes.