請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76383
標題: | 五種林木種子對乾燥的敏感性與微細構造 Desiccation Sensitivity and Ultrastructure of Five species of Tree Seeds |
作者: | Chuan-Hsiu Cho 卓娟秀 |
出版年 : | 1998 |
學位: | 碩士 |
摘要: | 本論文是以波羅蜜(Artocarpus heterophyllus Lam.)、大葉楠(Machilus japonica var. kusanoi Hayata)、青剛櫟(Cyclobalanopsis glauca (Thunb.) Oerst.)、長葉木薑子(Litsea acuminata (Blume) Kurata)與銀合歡(Leucaena leucocephala Lam.)等台灣低海拔不同生育地的林木種子為材料,觀察新鮮種子外形、胚的主軸(embryo axes)的形態與解剖特色及種子中不可溶儲藏物質的化學成份,並探討乾旱處理對種子存活力的影響。此外,亦觀察五種種子的胚軸、胚芽及胚根頂端分生組織之微細構造的差異及比較各種胚的主軸受到乾燥處理後在微細構造上的變化。 由實驗結果顯示五種種子的體積以波羅蜜最大而銀合歡最小,然而此二種子胚的主軸大小相似,其餘三種的胚軸較小;各胚軸在種子成熟採收時大多已發育,但可見4?6枚初生葉包被在胚芽外,然而青剛櫟僅為一團尚未明顯分化的細胞。大葉楠、青剛櫟及長葉木薑子等種子的子葉及胚軸內均具有分泌細胞或油細胞,波羅蜜的胚軸與子葉中含有乳汁管,而單寧細胞則普遍存在於各種子路軸的皮層與表皮組織、初生葉及根帽組織中。 種子胚軸中不可溶性的儲藏物質,以澱粉粒、蛋白質體及油滴為主。波羅蜜、大葉楠與長葉木薑子的胚軸基本組織細胞中可見澱粉體,而油滴則分佈於胚軸組織的細胞質中以及胚芽與胚根分生組織細胞的邊緣。銀合歡胚的主軸細胞的邊緣與蛋白質體的外圍密佈小油滴。除銀合歡外,各胚軸中較少見蛋白質體的存在。 成熟採收的五種種子的含水率以波羅蜜(61.03%)最高,而銀合歡(6.7%)最低;就新鮮種子的發芽率而言,則分別為60%、95.04%、96%、93.33%、94%。經過氯化鋰飽和鹽溶液乾燥處理後的種子,經萌發實驗的結果得知,波羅蜜、大葉楠、青剛櫟、長葉木薑子各種子若分別失去其含水量的6%、7.5%、17%、35%,則發芽率急速降低;若儲存於4℃的環境下,各種子保存活力的時間以銀合歡最長而波羅蜜最短。故而這些種子對乾燥的敏感性,由強到弱分別為波羅蜜、大葉楠、青剛櫟、長葉木薑子、銀合歡。 觀察各種子胚芽與胚根頂端分生組織細胞的微細構造,顯示此二部份的細胞質濃厚,細胞核大而明顯,佔細胞空間的20?30%;細胞質中液胞所佔的比例則依種類的不同而大小不一。在粒線體、內質網、色素體等胞器發育狀況與分佈的觀察中,銀合歡的細胞質中少見各種胞器,其餘四種則顯見各胞器的存在與活動的跡象。 當種子受到乾旱產生水分逆境時,在種皮、子葉與胚的主軸外觀上出現明顯的皺縮現象,含水率也明顯下降。透過微細構造的觀察,胚芽分生組織細胞隨著含水率的下降,出現液胞癒合或液胞膜破裂,各胞器的形態與相對空間位置改變、細胞核與核仁變形、原生質質離與細胞邊緣出現小囊泡化等現象;在胚根的分生組織細胞內有類似的變化但較不明顯,而根帽部份的細胞則出現明顯的原生質離現象,細胞中液胞化的現象也較胚根頂端分生組織明顯。 對乾燥敏感性較低的種子,通常其胚芽及胚根頂端分生組織細胞的細胞質較濃厚,液胞極小或沒有,細胞儲藏物以油滴與蛋白質體為主;隨著乾燥敏感性提昇,胚主軸頂端分生組織細胞的液胞化現象增加,各胞器亦呈相對程度的增加或出現活化狀態,並與種子萌發的第一發芽時間成正相關。本研究的五種種子中,對乾燥敏感性最強的波羅蜜種子的胚芽與胚根頂端分生組織細胞內具有高度液胞化的現象,與其他敏感性較弱的種子間呈現顯著差異;而就其他乾燥敏感性程度不同的種子與銀合歡種子比較,其液胞化程度亦呈顯著差異,但彼此間則差異不大。 Artocarpus heterophyllus Lam., Machilus japonica var. kusanoi Hayata, Cyclobalanopsis glauca (Thunb.) Oerst, Litsea acuminata (Blume) Kurata and Leucaena leucocephala Lam. are five woody species distrributed in the low forests of Taiwan. This thesis investigated their seed morphology and the anatomical characteristics, including the composition of insoluble storage materials, the ultrastructure of plumule and apex of radicle of the embryo axes. Besides the effects of desiccation on the seed viability and the ultrastructure of embryo axes were studied. The results showed that Artocarpus has the biggest seed mass, however, the size of its embryo axes is similar to that of Leucaena. Among the five species the seed of Leucaena is the smallest one. With the exception of Cyclobalanopsis, all the other embryo axes in matured seed are full-grown and generally with 4-6 primary leaves. In the cotyledons and embryo axes of the seeds of Machilus, Cyclobalanopsis and Litsea there are secretory mucilage or oil cells. The seeds of Artocarpus obviously contain laticifers in the cotyledons and embryo axes. However, tannic cells are ubiquitously distributed in the cortex and epidermis of embryo axes, primary leaves and root caps of the seeds. The predominant compositions of insoluble storage materials in the seeds of these five species are starch grains, protein bodies and oil droplets. The starch grains are distributed in the ground tissue of embryo axes of Artocarpus, Machilus and Litsea.. The oil droplets are located in the cytoplasm of the cells of embryo axes and in the marginal areas of the cells of plumule and radicle apex. Nevertheless, in the seeds of Leucaena, the oil droplets are mostly observed around the proteins bodies in the peripheryn of the cells in he embryo axes. The highest and lowest moisture contents of mature seed are fong in Artocarpus (61.03%) and Leucaena (6.7%) respectively, and the rates of germination are 60% (Artocarpus), 95.04% (Machilus), 96% (Cyclobalanopsis), 93.33% (Listea) and 94% (Leucaena). When the seeds were lost dehydrated 6% (Artocarpus), 7.5% (Machilus), 17% (Cyclobalanopsis), 35% (Lacumunata) of their moisture contents by the saturated lithium chloride (LiC1), the rate of germination decreased dramatically. Among the five woods, the seed of Lacumunata are the most resistant to low temperature storage (4℃) and seed of Artocarpus are more susceptable to low temperature treatment. These results suggest that the degrees of desiccation susceptibility of these seeds are Artocarpus, Machilus, Cyclobalanopsis, Litsea and Leucaena. The ultrastructural study on the seeds showed the cells of plumule and radicle apex has dense cytoplasm, and a large nucleus occuping 20-30% of the cell volumn. The size of vacuoles in the cytoplasm widely varies with the species. In the cytoplasm of Leucaena, the mitochondria, endoplasmic reticulum and plastids are seldom observed, however, in other species these organelles are ubiquitous distributed and metabolic active. During the drought stress, the seed coat, cotyledon and embryo axes are obviously shrunk. The ultrastructural change in the cells of plumule apical meristem are fusion or lysis of tonoplast, deformation of nucleus and nucleolus, shrinkage of protoplasm, and formation of small vesicles in the cell periphery. A similar, but less significant change was observed in the radicle apex, however, the cells in the radicle showed dramatic plasmolysis and vacuolation. In summary, the present study suggested that the more resistant to the desiccation a seed, the more densely of the cytoplasm in the cells of apex of plumule and radicle. Besides, in the desiccation resistant seeds the vacuoles are small or lack, and the predominant storage compounds are oil droplets and protein bodies. The vacuolation of the apical meristematic cells and the activity and the quantity of organelles in the cells of embryo axes are increased with the desiccation susceptibility of the seeds. In the seeds of the five studied species, highly vacuolation was only found in the plumule and radicle of Artocarpus seed, and the degree of vacuolation in the other four species is not significantly different, but is highly associated with their desiccation susceptibility. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76383 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
文件中的檔案:
沒有與此文件相關的檔案。
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。