Yamazaki Jun, Miyoshi Kazumitsu
College of Agriculture, Tamagawa University 6-1-1 Tamagawagakuen, Machida, Tokyo, 194-8610, Japan.
Ann Bot. 2006 Dec;98(6):1197-206. doi: 10.1093/aob/mcl223. Epub 2006 Oct 27.
Many Orchidaceous species are threatened globally by development and over-collection from their natural habitats for horticultural purposes. Artificial propagation from seeds is difficult in most terrestrial orchids native to temperate regions. Seed production is another limiting factor in the artificial propagation for these species because of the lessened probability of pollination and the destruction of fruit by insect larvae. Members of the genus Cephalanthera are distributed across Europe, Asia and North America. C. falcata is a temperate species of East Asia and an endangered species in Japan. As successful propagation from seeds of this species has never been reported, a reproducible method is described here for seed production in situ and propagation using immature seeds in asymbiotic culture in vitro.
Effects of hand-pollination and bagging treatment of ovaries were examined. Young capsules were collected every 10 d from 50 d after pollination until 120 d after pollination. Immature seeds obtained from these capsules were cultured asymbiotically on modified Kano medium and ND medium. Seed viability was examined within TTC (2,3,5-triphenyl tetrazolium chloride) test solution and histological observations were made on viable seeds by paraffin embedding at each collection stage.
Hand-pollination followed by bagging treatment of ovaries with aluminium foil was effective for insect control during fruit development, and successfully yielded capsules. Of the capsules, 74.5 % survived to full maturity. The highest frequency (39.8 %) of seed germination was obtained with seeds harvested 70 d after pollination. The frequency declined with progress of seed maturity on the mother plant. Minimal germination was observed with seeds harvested 100 d or later after pollination. Histological observation suggests that accumulation of such substances as lignin in the inner integument surrounding the embryo during seed maturation plays an important role in induction of dormancy.
许多兰科植物在全球范围内受到威胁，因其自然栖息地因园艺用途而遭到开发和过度采集。对于大多数原产于温带地区的地生兰花来说，通过种子进行人工繁殖很困难。种子生产是这些物种人工繁殖的另一个限制因素，这是由于授粉概率降低以及昆虫幼虫对果实的破坏。头蕊兰属的成员分布于欧洲、亚洲和北美洲。镰叶头蕊兰是东亚的一种温带物种，在日本属于濒危物种。由于从未有过该物种种子成功繁殖的报道，本文描述了一种可重复的方法，用于该物种种子的原位生产以及使用未成熟种子在非共生体外培养中进行繁殖。
研究了人工授粉和对子房进行套袋处理的效果。从授粉后50天到授粉后120天，每隔10天收集一次幼嫩蒴果。从这些蒴果中获得的未成熟种子在改良卡诺培养基和ND培养基上进行非共生培养。在2,3,5 - 三苯基氯化四氮唑（TTC）测试溶液中检测种子活力，并在每个采集阶段通过石蜡包埋对有活力的种子进行组织学观察。
人工授粉后用铝箔对子房进行套袋处理，在果实发育期间对昆虫防治有效，并成功获得了蒴果。其中，74.5%的蒴果存活至完全成熟。授粉后70天收获的种子发芽频率最高（39.8%）。随着种子在母株上成熟度的增加，发芽频率下降。授粉后100天或更晚收获的种子发芽率极低。组织学观察表明，种子成熟过程中胚周围内种皮中木质素等物质的积累在诱导休眠方面起着重要作用。
