Standardization of sterilization protocol and culture medium for growth regulator-free direct organogenesis in Cordyline terminalis (L.) Kunth

The study was conducted at the Biotechnology-cum-Tissue Culture Centre, Baramunda, AICRP of Floriculture and Landscaping, Odisha University of Agriculture and Technology, Bhubaneswar, India to standardize surface sterilization protocols and assess direct organogenesis in 3 explants-nodal segments, shoot tips and leaf bits under free plant growth regulators (PGR) conditions in Cordyline terminalis (L.) Kunth. Six sterilization treatments involving ethanol, sodium hypochlorite and mercuric chloride (HgCl₂) at varying concentrations and durations were evaluated. Among all, 0.1 % HgCl₂ for 10 min (T₈) was most effective, resulting in the highest survival (75.03 ± 0.17 %), minimal fungal (10.52 ± 0.16 %) and bacterial (0 %) contamination and maximum aseptic cultures (79.48 ± 0.14 %). Nodal segments consistently outperformed other explants in survival and regeneration. Subsequent culturing of nodal segments on MS basal medium devoid of PGRs resulted in direct shoot and root formation in all treatments (T₁–T₈), with T₈ showing maximum cultures with direct organogenesis (6.67), shoots (6.00/explant), leaves (9.00/shoot), root length (7.67 cm) and number of roots (5.33). Additionally, seasonal influence was significant for explants collected during the winter season (November-December) with higher survival and lower contamination compared to those from other months. The findings establish an efficient, hormone-free regeneration protocol for C. terminalis, emphasizing the importance of optimized sterilization and seasonal timing. This approach offers a simplified and cost-effective alternative for commercial micropropagation of C. terminalis.