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 (H_2O_2) as a pre–disinfectant for sterilizing rhizome bud explants of Z. aethiopica followed by sterilization with sodium hypochlorite (NaOCl) or chlorine dioxide (ClO_2) to eliminate in vitro contamination. Results showed that application of 5% (w/v) H_2O_2 for 5 minutes followed by 1% (w/v) NaOCl or 60~180 mg·L–1 ClO2 for 15 minutes 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 H_2O_2 and ClO_2 synergistically optimized the disinfection efficiency and explants viability