Standardisation of prehardening and hardening techniques for in vitro derived piantlets of Dendrobium orchid hybrid Sonia-17

The piantlets of Dendrobium Hybrid Sonia - 17 were prehardened in liquid KC medium containing charcoal and brick pieces. The root number (18.73) and root length (5.49 cm) of the microshoots were the highest in the medium supplemented with IBA 5.0 mg/1. The prehardened piantlets survived better under in vivo condition than those which were not prehardened. Among the five pot mixtures used for hardening, the establishment of piantlets in terms of plant height, leaf size, new growth and root length was good in the medium consisting of charcoal + brick + cocopeat (1:1:1). However, the root number was the highest in pure charcoal medium. Spraying with half KC nutrient solution improved the growth and establishment of the in mire derived piantlets of Dendrobium Hybrid Sonia -17.