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題 名 | 臺灣油杉空粒種子形成原因的探討=Investigation of the Formation of Empty Seeds in Keteleeria davidiana (Franchet) Beissner var. formosana Hayata |
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作 者 | 何政坤; 張淑華; 蔡錦瑩; | 書刊名 | 臺灣林業科學 |
卷 期 | 15:2 2000.06[民89.06] |
頁 次 | 頁209-227 |
分類號 | 436.251 |
關鍵詞 | 臺灣油杉; 空粒種子; 花粉發芽; 毬果與種子發育; Keteleeria davidiana var.formosana; Empty seeds; Pollen germination; Cone and seed development; |
語 文 | 中文(Chinese) |
中文摘要 | 從1993年至1998年間觀察生長在台北植物園的台灣油杉天然受粉毬 果與種子的發育,結果發現有效種子率 (每毬果內飽滿種子數占潛力種子數的百 分率),每年均不到1%。大粒種子從多胚期到帶子葉胚期的組織切片顯示80%均 有受精,但發育到成熟胚的階段卻逐漸近乎完全敗育。毬果長度的生長很明顯的 受到其內的大粒種子數的影響,二者之間呈極顯著的線性迴歸關係。毬果與胚珠 在準備受精前已發育到與成熟毬果與種子大小一般。台灣油杉的花粉發芽率高且 在授粉期時可在胚珠的珠孔中發現花粉粒,顯示雌雄毬花間的授粉並無困難。未 受粉的毬果所含的種子均屬小粒而且不會掉落。這些觀察都顯示胚珠接受到花粉 後才會發育並刺激毬果生長,所以胚珠受粉率的多寡會影響大粒種子的產率及毬 果的大小。六年間台灣油杉大粒種子的變異可從每毬果50粒到114粒,毬果長 度可從6.7到9.0 cm。依據大粒種子產率最高的1年來估測空粒種子產生的因素, 可以推估如下:依據每個可孕性鱗片所含2粒種子的鱗片數,潛力種子數約有 206粒,再依此值算出受粉前後胚珠敗育率、受精前敗育率、胚敗育率、及有效 種子率分別為33%、27 %、39%及<1%。因此在受粉效率最高的一年,受精胚 的敗育是種子空粒形成的主要因子。 |
英文摘要 | Cone and seed development was observed from 1993 to 1998 in wind- pollinated Keteleeria davidiana (Franchet) Beissner var. formosana Hayata trees grown at Taipei Botanical Garden. Seed effici-encies per cone (percent filled seed per cone divided by seed potential) were persistently less than 1% during the investigation period. Sections of large seeds at different stages during the period from polyembryos to cotyledonary embryos revealed that 80% of them were successfully fertilized initially, and then almost all degenerated before developing into mature embryos. Cone length growth was evidently affected by the number of large seeds inside the cone, and there was a very significant (p < 0.001) linear regression between these 2 factors. Before fertilization occurred, conelets and ovules reached the same sizes as did mature cones and seeds. Pollen grains had a high germination percentage and were found in mycropyles of ovules, indicating no pollination barrier between catkins and conelets. Unpollinated cones containing small seeds were not shed. All these facts indicate that ovules grew after they obtained pollen, subsequently stimulating cone development. The great variations of large seeds, numbering from 50 to 114 per cone, and cone length, differing from 6.7 to 9.0 cm, in 6 years came from the pollination degree of ovules. According to the year with the best large-seed production, the reasons for empty seeds could be estimated as follows: Seed potential per cone calculated as 2 times the number of fertile ovuliferous scales was about 206 seeds. Percentages of seed losses resulting from pre- and post-pollination ovule abortion, prezygotic factors, embryo degeneration, and efficient seed were 33%, 27%, 39%, and <1%, respectively. Even in the year with good pollination effectiveness, embryo degeneration was so great as to cause most fertilized seeds to become empty. |
本系統中英文摘要資訊取自各篇刊載內容。