37个玉兰品种的花粉形态及数量分类研究

The Research on Pollen Morphology and Numerical Taxonomy of 37 Yulania Varieties

为了探讨玉兰品种间的花粉形态差异,为众多玉兰品种的分类鉴定、起源及演化提供依据,本研究对37个玉兰品种的花粉形态进行了电镜扫描观察。分析显示,其花粉形态相似,均为左右对称,异极,具单沟,超长球形(P/E>2),大小(52.9~61.3μm)×(21.3~27.6μm),属于NPC花粉分类系统中的N1P3C3类型,与玉兰亚属植物花粉共同的典型特征一致,但表面纹饰的细微形态结构(穿孔和孔穴的分布密度,纹饰类型等)存在较大差异,表明花粉的外壁纹饰可以作为区分玉兰品种的参考依据。孢粉学性状的数量聚类可清晰地将供试玉兰品种区分为白玉兰类群与二乔玉兰类群,说明可以将孢粉学特征作为玉兰品种的一级分类方法,但若单独用其区分玉兰品种是否为一级品种则分辨率还不够,所以该特征仅可以作为品种分类的辅助参考指标。

In order to explore the difference of pollen morphology among different Yulania varieties, so as to provide the reference for the identification, origin and evolution of Yulania varieties, we scanned the pollen morphology of 37 Yulania varieties with electric mirror in this study. The results showed that the pollen morphology of Yulania varieties was similar. All the pollen gains were bilateral symmetry, hemimorphic, having 1-colpate and were perprolate （P/E〉2）. In addition, their size was （52.9-61.3 μm）×（21.3-27.6 μm）, belonging to pollen gain types of N1P3C3. What＇s more, the pollen morphology of 37 varieties was in accordance with the typical characteristic of subgenus Yulania, while some had tiny different exine ornamentation in their pollen gains （the density of perforations and caves, types of exine ornamentation and so on）, indicating the exine ornamentation of pollens could be regarded as the reference to distinguish Yulania varieties. Quantitative clustering of palynological characters could clearly make a distinction between M. denudata and M. soulangeona, which sugg- ested that palynology might be a fine method for species classification of Yulania. However, if it was used alone to distinguish whether the Yulania variety wass a grade one, the resolution was not enough, so this feature could only be used as an auxiliary reference index for cultivar classification.