公告日期 : 2012-05-10
Seed Germination and Storage of Cycas taitungensis (Cycadaceae)
Authors：Ching-Te Chien, Shun-Ying Chen, Shu-Hwa Chang, Jeng-Der Chung
Cycas taitungensis is endemic to an area of about 290 ha in Taitung County, eastern Taiwan. However, this species has been attacked by a scale insect (Aulacaspis yasumatsui) and larvae of thebutterfly, cycad blue (Chilades pandara peripatria), and many plants have died in the last 20 yr. To establish ex situ conservation of C. taitungensis, seeds were collected from a managed plantation and the Cycas taitungensis Nature Reserve for germination. Some of the seeds from the plantation were stored at 5℃ for 8 and 16 mo and germinated at 30/20℃ to test germinability. The embryo length was measured during seed incubation at 25/15 and 30/20℃. Germination of seeds from 2007 from the plantation began in weeks 17~18, and final germination was about 58~60% at 30/20, 25/15, and 25℃ incubation. Germination of seeds from 2008 from the same plantation began in week 18, and final germination percentages were 13, 64, 75, and 84% at 20/10, 25/15, 30/20, and 25℃ incubation temperatures, respectively. Thus, favorable germination temperatures were 30/20 and 25℃. Initial germination of seeds from 7 individual plants from the Nature Reserve extended from weeks 3 to 18, and final germination ranged 30~88%. These differences may have been due to the wide range in time of pollination in the Nature Reserve, thus resulting in different degrees of seed maturity. Fresh seeds air-dried for 24 h and stored at 5℃ for 16 mo retained their original germination, whereas seeds stored with moist moss at 5℃ for 16 mo showed decreased germination from 73% (fresh seeds) to 50%. Cold storage at 5℃ shortened the time to begin seed germination regardless of the storage conditions with or without moist moss. The underdeveloped embryo of C. taitungensis seeds must increase in length by about 117% before seed germination can occur. We concluded that seeds of C. taitungensis exhibit morphophysiological dormancy, a high temperature at 30/20 or 25℃ increases seed germination, and air-dried seeds can be stored at 5℃ for at least 16 mo.