蘭之胚培養

Embryo Culture of Orchids

蘭科植物成熟果莢內所含的種子非常小，不含胚乳，胚未分化，祗達圓球胚階段（globular embryo stage），沒有子葉、胚根、胚芽。當此圓球胚沿縱軸有大小細胞之區別後，經胚培養（即無菌播種），則於人工培養基內迅速發育成幼小植株。從型態及解剖學上探討，臺灣一葉蘭胚之發育似禾本科穀穎，而蝴蝶蘭胚之發育則如單子葉中之洋蔥和鬱金香。二者之原球體（protocorm）功用類似子葉。至於蕙蘭屬中之素心蘭，成熟種子的胚，祇達原胚至圓球胚階段，胚內細胞少且未極化，胚培養較為困難，此原胚於培養基內，發芽先形成根莖，再分化出芽和根，將之歸為蕙蘭型。而根莖之功用亦類似子葉。作者就數種蘭類種子發芽及形態發生觀察之結果，認為蘭種子發芽容易與否，與種子成熟時其內胚發育程度有密切關係，不易發芽者係胚培養問題，而非種子休眠問題。

Orchid seeds are exceedingly small, but produced in large number. The embryos at globular stage, as seeds mature, consist of relatively undifferentiated cells. Cells of the posterior end are larger, and the anterior end are smaller in size and denser by staining. They have no endosperm, no cotyledon and no root initials. Morphological and anatomically examination of the embryo development in Pleione formosana is similar to the embryogenesis of cereal while in Phalaenopsis white hybrid is similar to the embryogenesis of onion and tulip. The embryos at proembryo-globular stage as seeds mature in Cymbidium ensifolium var misericors. The embryos consist of mostly isodiametric cells, and lesser in number as compared with Pleione and Phalaenopsis embryos. The seeds are hard to germinate. After germination, the embryos differentiate rhizomatous organs, then seedlings are formed from rhizome. It seems likely that developmental stage of embryos in mature seeds are correlated to the easy or hard germinating seeds in orchids.