Supplementary effect of hydrogen peroxide as a pre-disinfectant for sterilizing rhizome bud explants of Zantedeschia aethiopica L. With Chlorine Dioxide

Zantedeschia spp. (calla lily) are ornamental tuberous/rhizomatous plants of economic importance worldwide. In vitro micropropagation techniques have been widely used to mass-produce virus-free calla lilies. However, effective removal of contaminants is a major problem for the in vitro establishment of the calla lily propagation. In this study, we applied hydrogen peroxide (HjOJ as a pre-disinfectant for sterilizing rhizome bud explants of Z. aethiopica followed by sterilization with sodium hypochlorite (NaOCl) or chlorine dioxide (ClO₂) to eliminate in vitro contamination. Results showed that application of 5% (w/v) H₂O₂ for 5minutes followed by 1% (w/v) NaOCl or 60-180 mg-L"1 ClO₂ for 15minutes significantly reduced the contamination rate to < 38% while maintaining the vigor of explant tissues. Surviving explants sterilized with H₂O₂ followed by ClO₂ exhibited a higher rate (>75%) of those showing shoot development than those sterilized with NaOCl (54%). The two-step sterilization method with H₂O₂ and ClO₂ synergistically optimized the disinfection efficiency and explants viability.