Abstract

Stevia rebaudiana belonging to family Asteraceae is a natural sweetener crop and seems to be a alternative crop for diversification in Indian agriculture. Stevia produces sterile seeds and the availability of cuttings is seasonal and limited. Tissue culture plants of stevia are genetically pure, free from pathogens and have excellent vigour. In the present studies, in vitro propagation of stevia was attempted through direct shoot regeneration from nodal explants. Murashige and Skoog (MS) medium supplemented with various concentrations of cytokinins (BA, Kin) and auxins (NAA, IAA and IBA) alone and in combinations with each other was used for shoot induction, multiplication and rooting of regenerants in vitro. The maximum nodal explants survival (100%) was observed by sterilizing the nodal explants with NaOCl (1.0%) for 15 min→Bavistin (0.2%) for 15 min→Streptocyclin (0.1%) for 15 min→HgCl2 (0.1%) for 3 min. Highest shoot induction (95.6%) in 7.8 days was observed on the medium MS+BA 1.5 mg/l+Kin 1.5 mg/l +IAA 0.5 mg/l+Ascorbic acid 20 mg/l+Citric acid 40 mg/l). Addition of antioxidants (Ascorbic acid 20 mg/l and citric acid 40 mg/l) in the establishment medium proved effective in checking the release of inhibitory substances from the explants in the media resulting in synergistic effect on the shoot induction. Comparatively low shoot regeneration (93.7%) was recorded on MS basal medium supplemented with BA 1.5 mg/l+Kin 1.5 mg/l+IAA 0.5 mg/l and devoid of additives (Ascorbic acid 20 mg/l and citric acid 40 mg/l). Maximum shoot proliferation was obtained on the medium MS basal+BA 2.0 mg/l+Kin 2.0 mg/l+IAA 0.5 mg/l after 30 days of culturing. Half strength MS basal medium fortified with IBA (0.5 mg/l) exhibited maximum rooting (92%) and average root number/culture with 8.6 days to rooting. Acclimatized plantlets were transplanted successfully under field conditions and during hardening 100% survival of plantlets was observed on potting mixture containing sand+ soil+ vermicompost (1: 1: 1).