Camellia japonica L. is highly valued for its ornamental and industrial applications. However, existing limitations in conventional seed and cutting propagation necessitate the development of a stable and efficient mass propagation system. This study systemically optimized each critical stage of in vitro culture—including shoot and root development, multiple shoot induction, rooting, and acclimatization —and quantitatively assessed the overall efficiency using integrated indices. Shoot growth was most vigorous on Woody Plant Medium (WPM) without the addition of indole-3-butyric acid (IBA), while root development was notably promoted by Murashige and Skoog (MS) medium supplemented with IBA. The highest number of multiple shoots was produced using basal explants cultured on MS medium containing 0.5 mg/L thidiazuron (TDZ), yielding an average of 2.67 shoots per explant. Optimal root induction was observed following a 15-min pulse treatment with 500 mg/L IBA (producing 24,33 roots), whereas the root elongation was maximized by a 5-min treatment with 1000 mg/L IBA (2.10 cm). Acclimatization successfully resulted in 100% survival in both tested substrates (A: peat moss, perlite, and cocopeat mixed in a 3:1:1 ratio; B: peat moss, perlite, and vermiculite mixed in a 1:1:1 ratio), with substrate B promoting a greater increase in plant height. Normalized growth parameters were averaged to calculate the Camellia Micropropagation Index (CMI). Integrated analysis identified the most efficient treatments as: WPM without IBA (shoot growth), MS with IBA (root growth), MS + 0.5 mg/L TDZ with basal explants (multiple shoots), 1000 mg/L IBA for 5 min (rooting), and substrate B (acclimatization). Despite these optimal conditions, considerable variation within treatments suggests that further fine-tuning or long-term evaluation is necessary to improve reliability. These findings provide a robust guideline for establishing a successful in vitro mass micropropagation system for C. japonica.

Abstract
Introduction
Materials and Methods
    1. Plant materials
    2. Culture media and conditions
    3. In vitro shoot and root growth experiment
    4. Multiple shoot induction experiment
    5. In vitro rooting experiment
    6. Acclimatization experiment
    7. Evaluation of propagation efficiency
    8. Statistical analysis
Results and Discussion
    1. Shoot and root growth responses under basalmedia with or without IBA
    2. Multiple shoot induction
    3. In vitro root induction
    4. Acclimatization
    5. Analysis of propagation efficiency
References

• Do Hyun Kim(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Kwan Been Park(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Seung A Cha(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Ji Hyeon Lee(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Seon A Kim(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Jenna Jung(Graduate student, Division of Forest Environmental Resources, Gyeongsang National University, Jinju 52828, Korea)
• Myung Suk Choi(Professor, Division of Forest Environmental Resources and Institute of Agriculture of Life Science, Gyeongsang National University, Jinju 52828, Korea) Corresponding author