Influence of AGNO3 on zygotic embryo culture as an efficient tool for conservation of a vulnerable medicinally important forest tree Oroxylum indicum (l) kurz.

The present investigation has been carried out to study the influence of AgNO3 on in vitro zygotic embryoculture in Oroxylum indicum (L) Kurz (Bignoniaceae), a vulnerable, medicinal forest tree. The zygotic embryos were cultured on MS medium augmented with different concentrations (1.0-7.0 mg/L) of BAP/KIN/TDZ individually and also in combination with 0.1 mg/L AgNO3. More number of multiple shoots (20±0.82) /explant was observed at 5.0 mg/LBAP. Whereas 0.1 mg/L AgNO3 +3.0 mg/L TDZ had induced the maximum number of shoots (32±0.02)/explant in comparison to all other PGRs used. When the explants with multiple shoots subcultured on the same concentration and combination of PGRs showed the enhancement in multiple shoots proliferation. The micro-shoots developed in vitro were excised, shifted on to MS +1.0 mg/L GA3 for elongation. These elongated micro-shoots were cultured on ½ strength MS + 20 gm/L sucrose+0.5- 3.0 mg/L IAA/IBA/NAA for in vitro rooting. Ex vitro rooting was also observed in micro-shoots developed through zygotic embryoculture. After in vitro and ex vitro rooting, plantlets were successfully acclimatized followed by transfer into research field and were found to be morphologically similar to donor plants. Thus, the protocol developed during the present investigation can be utilized for the mass scale multiplication and conservation of this valuable vulnerable medicinal plant.