栽培红花山玉兰的传粉生物学

研究了栽培红花山玉兰（Ｍａｇｎｏｌｉａｄｅｌａｖａｙｉ）的开花生物学和传粉生物学特性，并探讨了红花山玉兰只开花而不结实的原因以及提高其结实率的技术措施。红花山玉兰的花被片为９，呈３轮排列。外轮花被片先张开，而内２轮花被片仍紧密地包裹着雌雄蕊群，约２４ｈ后，内２轮花被片才张开。在外轮花被片张开而内２轮花被片未张开时，柱头就有授粉能力，但雄蕊尚未成熟。因内２轮花被片紧密地包裹着雌雄蕊群而阻碍了传粉者进入花内传粉。当内２轮花被片张开时，雄蕊成熟，花药裂开而散发花粉；柱头外露，但此时的柱头已变棕红色，完全失去了授粉能力。若外轮花被片刚张开时，去掉全部花被片，蜜蜂可成为有效传粉者，其结果率可达到５３．３％；若去掉全部花被片，并施以人工异花授粉，其结果率可高达１００％。研究结果表明，红花山玉兰是雌雄异熟的，且异花授粉是亲和；其开花生物学特性适合甲壳虫携带花粉进入花内传粉。红花山玉兰只开花而不结实的原因可能是其开花生物学特性所要求的携带花粉进入花内传粉的甲壳虫无法进入花内传粉或者缺乏。

Pollination Biology of Cultivated Magnolia delavayi

Magnolia delavayi has two flower types, i.e, white - and red -flowered types. The white-flowered type, mainly distribted in Yunnan, Sichuan and Guizhou Provinces, China, has fruit-set capability in nature, but it is difficult to set fruits in cultivation condition. The red-flowered type, recently discovered in Yunnan, China, is found very difficult to set fruits in nature and almost fruitless under the cultivated condition. This study examines the characteristics of floral and pollination biology in red-flowered Magnolia delavayi cultivated in Kunming Botanical Garden. The maturity of gynoecium is about 24 hr earlier than that of androeciun. While the outer whorl of tepales opens, stigmas are receptive, but stamens are immature and anthers don't dehisce. The inner whorl of tepales closely envelops stigmas, pollinators don't get inside for transferring pollen to receptive stigmas. While the inner whorl of tepals opens, stamens matured, but stigmas changed into an unreceptive state. Based on the observation mentioned above, an attempt to increase the fruit-set rate was carried out, When the outer whorl of tepals has been conspicuous opening , all tepals were completely removed, stigmas were convenient for bees to pollinate, and the fruit-set rate are increased to 53.3%, However, by using hand pollination, the fruit-set rate are increased to almost 100%.