Seed Germination and Storage of Cycas taitungensis (Cycadaceae)

台東蘇鐵種子發芽與儲藏

簡慶德(Ching-Te Chien) ； 陳舜英(Shun-Ying Chen) ； 張淑華(Shu-Hwa Chang) ； 鍾振德(Jeng-Der Chung)

《台灣林業科學》 27卷1期 (2012/03) Pp. 1-11

https://doi.org/10.7075/TJFS.201203.0001

摘要

台東蘇鐵是台灣特有種植物，僅分布在台東縣轄區，面積約290公頃。過去20年間許多的台東蘇鐵因遭受白輪盾介殼蟲和東陞蘇鐵小灰蝶幼蟲為害死亡。為建立台東蘇鐵區外保育，採自林務局設置的台東蘇鐵自然保留區和台東大武鄉一處私人經營的台東蘇鐵栽種區的種子，分別進行不同溫度的種子發芽試驗。另外，採自私人栽種區的種子部份於5℃儲藏8個月和16個月，取出後在30/20℃下發芽，以瞭解台東蘇鐵種子儲藏後之發芽能力。種子胚長度量測亦在種子播種後同時進行。2007年採自私人栽種區種子開始發芽時間是在第17～18週，發芽率在30/20、25/15和25℃下達58～60%；採自同地區2008年種子開始發芽時間是在第18週，發芽率在25℃下最高達84%，在30/20、25/15和20/10℃下分別為75、64和13%。因此，適合台東蘇鐵種子發芽溫度為30/20和25℃。採自台東蘇鐵自然保留區7株台東蘇鐵種子，開始發芽時間從第3週至第18週不等，且發芽率從30%至88%不等，這些差異可能是保留區母株間受粉時間不一，導致種子成熟度不同所引起的。台東蘇鐵種子經室內空氣乾燥24小時，於5℃儲藏16個月後仍能保持原有新鮮種子的發芽率，但種子與濕水苔混合於5℃儲藏16個月，發芽率從新鮮種子73%降至50%，顯示種子乾藏比濕藏佳。乾、濕種子儲藏於低溫5℃皆能縮短開始發芽的時間。台東蘇鐵種子有發育不完全胚，胚長度必須增加約1.17倍，胚根才會突破種皮發芽。結論台東蘇鐵種子有形態生理的休眠，高溫30/20℃和25℃增加種子發芽率，種子陰乾24小時後可儲藏5℃至少16個月。

關鍵字

台東蘇鐵 ； 形態生理的休眠 ； 種子發芽 ； 種子儲藏 ； 發育不完全胚

並列摘要

”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 the butterfly, 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.

並列關鍵字

Cycas taitungensis ； morphophysiological dormancy ； seed germination ； seed storage ； underdeveloped embryo