Establishment of a refined somatic embryogenesis protocol and light-spectrum-based acclimatization in Caladium bicolor ‘White’

This study aimed to develop an efficient protocol for direct somatic embryogenesis (SE) from leaf explants of Caladium bicolor 'White' and to assess the impact of different light spectra on ex vitro acclimatization of regenerated plantlets. Leaf segments of C. bicolor were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) (0.5, 1.0, and 1.5 mg L^-1) alone or in combination with 1 mg L^-1 6-benzyladenine (BA). Leaf cuttings with direct somatic embryos were subcultured on MS medium supplemented with four concentrations of BA (0.5, 1.0, 1.5 and 2.0 mg L^-1) for shoot regeneration. Regenerated plantlets of SE were then acclimatized under four light spectra: red (R), blue (B), combined blue-red- (BR), and white (W) fluorescent light. Morphological, physiological, and biochemical traits were evaluated. The highest somatic embryogenesis (31.25%) was observed in the treatment with 1.5 mg/L 2,4-D + 1.0 mg/L BA (T6), compared to just 1.25% in the 0.5 mg/L 2,4-D alone treatment (T1). Organogenesis was significantly enhanced at 2.0 mg/L BA, producing up to 6.33 shoots and 55.33 roots per jar, compared to ~ 2.00 shoots and ~ 1.00 root in the lowest BA treatment. During acclimatization, plantlets grown under blue LED light showed superior vegetative performance with the highest plant height (5.98 cm), leaf number (28.6), and root weight (1.79 g), while white fluorescent light (control) resulted in the poorest outcomes across most traits, including plant height (3.08 cm) and root weight (0.94 g). The study establishes a reproducible SE protocol for C. bicolor and highlights the critical role of blue and red light spectra in enhancing acclimatization. These findings provide a foundational framework for commercial-scale propagation and light optimization strategies in ornamental plant tissue culture.