Micropropagation and conservation strategies of the potentially medicinal and economically-important tropical deciduous tree - Drypetes roxburghii (Wall.) Hurursawa

The present study was designed to understand seed germination barriers and to develop an efficient micropropagation system in Drypetes roxburghii. Fresh seeds with coats removed, cultured on MS medium supplemented with + 1.4 μM gibberellic acid (GA3) + 0.01% activated charcoal (AC) resulted in maximum (83.30 ± 0.63%) seed germination with healthy seedling development. Cotyledonary nodal explants showed best shoot proliferation on Murashige and Skoog (MS) medium supplemented with 1 μM 6-benzylaminopurine (BAP) with maximum number of shoots (1.80 ± 0.24) and shoot length (4.10 ± 0.34 cm). The combination of hormones did not show any significant effect compared with the individual cytokinins tested. The maximum number of shoots (1.70 ± 0.26) with shoot length 3.44 ± 0.22 cm was observed on MS medium supplemented with 1 μM BAP + 2 μM kinetin (Kn). In encapsulation experiments, the nodal explants encapsulated with liquid MS medium + 2 μM BAP + 3% sucrose + 3% sodium alginate showed maximum shoot sprouting (1.70 ± 0.33) on MS medium supplemented with 1 μM BAP + 3% sucrose. The in vitro derived shoots were best rooted on MS medium supplemented with 2 μM IBA with maximum number of roots (2.10 ± 0.34) and root length (6.21 ± 0.24 cm) per shoot. The plantlets developed in vitro were successfully established under field conditions with 90% survival rate.   Key words: Seed germination, micropropagation, phytohormones, synthetic seeds.