In vitro rooting and ex vitro acclimatization protocol for Cordyline terminalis (L.) Kunth

An efficient in vitro rooting and ex vitro acclimatization protocol was developed for Cordyline terminalis (L.) Kunth, commonly known as the Ti plant, an economically important ornamental foliage species. The study was conducted at the Biotechnology-cum-Tissue Culture Centre, All India Coordinated Research Project (AICRP) on Floriculture and Landscaping, Odisha University of Agriculture and Technology, Bhubaneswar. Nodal segments were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of 6-benzylaminopurine (BAP), α-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) for shoot initiation and organogenesis. Among the combinations tested, BAP (1.0 mg L-1) and NAA (0.5 mg L-1) induced the highest shoot proliferation and morphogenetic response. For rooting, both in vitro and ex vitro approaches were evaluated. In vitro rooting was achieved on plant growth regulator (PGR)-free half-strength MS medium, while ex vitro rooting was optimized using quick dips in indole-3-butyric acid (IBA) at 25 ppm, which yielded the highest rooting percentage (96.6 %), root number (3.6) and root length (3.90 cm) in potting mixture. Hardening was performed under open conditions, plastic cover and net house environments using various substrates. The highest survival (40 %) was recorded in the net house using a vermiculite + sand substrate, which although moderate, represented the most effective survival outcome under tropical field conditions. Additionally, nutritional standardization trials revealed that soil drenching with nitrogen-phosphorus-potassium (NPK) (19:19:19) at 0.75 g plant-1 significantly improved plant height and leaf number, while foliar application enhanced leaf length and breadth. This comprehensive protocol demonstrates the potential for mass propagation of C. terminalis with high rooting efficiency and improved survival rate. The findings provide a practical, reproducible and cost-effective strategy for sustainable micropropagation and commercial-scale cultivation of this valuable ornamental species.