Abstract
This paper was designed to study seed germination and embryogenesis in Calanthe aristulifera, Calanthe izu-insularis and Calanth amamiana. The results may be summarized as follows.
1. The ovaries of C. aristulifera, C, izu-insularis and C. amamiana rapidly increased in size and reached their final size about 60 days, 50 days and 70 days, respectively after pollination.
2. The seed and embryos of C. aristulifera, C, izu-insularis and C. amamiana rapidly increased in size, and reached their final size 70 days and 80 days, respectively after pollination.
3. Ovule formation occurred 38 to 40 days after pollination in both C. aristulifera and C. izu-insularis, and 43 to 45 days after in C. amamiana.
Double fertilization occurred 48 to 50 days after pollination in both C. aristulifera and C. amamiana, and 43 to 45 days after in C. izu-insularis.
The mature embryo sac was observed to contain 5 to 6 nuclei regardless of species.
After pollination, C. aristulifera, C. izu-insularis and C. amamiana required 95 to 100 days for the completion of embryo development.
4. Proembryos of C. aristulifera, C. izu-insularis and C. amamiana on the tetrad stage were all classified as A2 type, according to Veyret′s classification. Similarly, embryos of C. aristulifera, C. izu-insularis and C. amamiana on and after the tetrad stage seemed to belong to the E type (Liparis pulverlenta type).
The mture embryo was observed to be derived from the apical cells of proembryo in C. aristulifera, C. izu-insularis and C. amamiana.
5. Three to five endosperm nuclei were observed in the embryosac after fertilization in C. aristulifera, C. izu-insularis and C. amamiana.
6. The seeds of C. aristulifera were able to germinate after the intermediary stage (80 days after pollination), those of C. izu-insularis after the time between the octant and intermediary stage (80 days after pollination), and those of C. amamiana before the tetrad stage (60 days after pollination).
The highest percentage of seed germination was obtained when the seeds were harvested near the mature embryo stage. When culturing C. izu-insularis for germination, dark conditions were better than light, and Hyponex medium was better than Murashige and Skoog medium.
