Abstract
The mature seeds of 7 Cymbidium species, including those from different climatic regions (temperate or tropical), with different life-forms (terrestrial or epiphytic), and different nutritional modes (autotrophic or mycoheterotrophic) were cryopreserved by vitrification to demonstrate the effectiveness of this method for germplasm preservation. The period of exposure to vitrification solution was initially optimized for seeds of 3 species, and the optimum periods were found to be 60 min for C. goeringii and C. macrorhizon seeds and 30 min for C. finlaysonianum seeds. Cryopreservation under optimum conditions did not have any deleterious effect on the seeds, and the germination rates of the cryopreserved seeds were as follows (these rates were almost identical to those of untreated control seeds): 32% for C. goeringii, 82% for C. macrorhizon, and 76% for C. finlaysonianum. The cryopreservation method was also successfully applied to the seeds of other members of the genus Cymbidium, although the period of exposure to the vitrification solution varied with life-form. The periods were optimized to 60 and 30 min for the terrestrial and epiphytic species, respectively. These results suggest that cryopreservation by vitrification has wide applicability for the seeds of several orchid species with varying ecological and physiological adaptations.
