An improved encapsulation protocol for regrowth and conservation of four ornamental species

The encapsulation technology, initially developed for clonal propagation through the production of synthetic seeds with somatic embryos, is currently proposed for use with non-embryogenic explants, such as buds and nodal segments (unipolar propagules). In the present study, the encapsulation procedure and its effect on shoot regeneration were evaluated. Apical buds isolated from shoot cultures of four ornamental species (Photinia × fraseri Dress., Polygala myrtifolia L., Metrosideros excelsa Soland. ex Gaertn., and Rosa) were encapsulated in 3% sodium alginate. Effects of complexation time, sucrose concentration, and storage temperature on the regrowth ability of propagules were assessed. With the appropriate combination of sucrose concentration and polymerization time, the encapsulated explants proved to have a better regrowth (80-100%) after sowing than the naked ones. In addition, medium-term storage of Metrosideros encapsulated explants promoted a high level of regrowth (74%) after 4 months in the dark at 10°C; while polygala beads were preserved up to 8 months regardless of storage temperatures. Potential current applications of encapsulation technology and the future use of beads in vivo conditions are also discussed.