Symbiotic and asymbiotic germination in vitro of Chloraea longipetala (Orchidaceae), an endemic orchid from Chile

Abstract

Chile has about 72 species of terrestrial orchids, most of them endemic. Some are threatened due to habitat loss, fires and herbivores damage and many have potential as ornamental plants or cut flowers. In vitro plant germination could be a key strategy for the long-term conservation and propagation of these species. In vitro asymbiotic and symbiotic, germination and subsequent embryo development in the orchid Chloraea longipetala were evaluated using five different culture media, aiming to provide efficient protocols for its propagation. For asymbiotic germination, we used water agar (AW), banana culture medium (CMB), tomato culture medium (CMT), oatmeal agar (OMA) and Malmgren terrestrial orchid medium (MM). For symbiotic germination, just AW and OMA were used. In addition, seed viability was estimated and reached 86.6 %. After four weeks, in all media except AW, the germination stage (embryo emerges from seed coat) was reached, for asymbiotic germination. However, there were no significant differences in the germination percentage among all five media, not exceeding 10 % in any treatment. After eight weeks, only seeds in MM reached the protocorm stage. On the other hand, symbiotic germination resulted in a significantly higher germination percentage (40 %), and embryos reached the rhizoid stage. For C. longipetala, unlike other Chilean species, the presence of orchidiod fungi seems to be necessary for successful and efficient germination and embryo development. This information is key for future propagation initiatives, for conservation, restoration or commercial applications as ornamental plants.