Optimization of growth regulators for efficient callus-mediated organogenesis in ornamental Cordyline

An efficient in vitro regeneration protocol was developed for Cordyline terminalis via indirect organogenesis using different explants and plant growth regulator (PGR) combinations. Nodal segments, shoot tips and leaf bases were cultured on Murashige and Skoog (MS) medium supplemented with varying 6-Benzylaminopurine (BAP), α-Naphthaleneacetic acid (NAA) and 2,4-Dichlorophenoxyacetic acid (2,4-D) concentrations. Among the explants, nodal segments showed the highest morphogenic response with early shoot initiation and maximum shoot production. The treatment with BAP 1.0 mg L-1 + NAA 0.5 mg L-1 (H3) recorded the highest callus induction (83.33 %), highest callus intensity (4.40) and callus index (367.00). Media supplemented with 2,4-D promoted early and dense callus formation but resulted in limited shoot regeneration. Callus tissues were subcultured at 3-week intervals onto fresh regeneration medium containing BAP (1.0 mg L-1) + NAA (0.5 mg L-1) to promote shoot differentiation. It resulted in the regeneration of multiple shoot primordia (up to 4-5 shoots per culture). Correlation analysis indicated a strong positive relationship between callus intensity and shoot proliferation efficiency. These results highlight the critical role of explant selection and hormonal balance in optimizing callus-mediated regeneration. The standardized protocol developed in this study can be effectively utilized for the large-scale propagation and conservation of Cordyline terminalis.