Abstract Pollen grains of 92 Bougainvillea genotypes were examined using a light microscope (LM) and scanning electron microscope (SEM) to identify taxonomic characteristics and the relationship between pollen morphology and germination capacity. The shapes of fresh pollen grains of Bougainvillea genotypes are spheroidal to prolate-spheroidal or suboblate after infolding. The sexine of Bougainvillea pollen grains consists of columellae and a reticulate cristatum, with or without microechini. The distribution pattern of the tectum microechini is uniform on the pollen grains within each genotype, yet it is variable among the different genotypes. Pollen with a smooth reticulate cristatum was observed in the genotypes of B. peruviana, while pollen with muri covering the cristatum were found in the genotypes of B. glabra and B. spectabilis. The pollen grains of each Bougainvillea germplasm have a wide range of diameters. The mean diameter of the pollen grains of the diploid genotypes ranged from 22.2 to 32.1 μm, while that of the polyploid genotypes ranged from 26.7 to 40.4 μm. The germinated pollen grains were observed in the diploid and tetraploid genotypes, the pollen germination rate of which was commonly less than 20 %. The size of germinated pollen grains was significantly larger than that of the silent ones, which indicated that the nonuniform distribution of grain size is a key reason for the low germination capacity of Bougainvillea pollen.

中文翻译：

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九重葛（Nyctaginaceae）花粉形态和活力的特征

摘要 使用光学显微镜 (LM) 和扫描电子显微镜 (SEM) 对 92 个九重葛基因型的花粉粒进行了检查，以确定分类特征以及花粉形态与发芽能力之间的关系。九重葛基因型新鲜花粉粒形状为球状至扁长球状或内折后近扁圆形。九重葛花粉粒的雌性由小柱和网状嵴组成，有或没有微棘。各基因型花粉粒上微棘顶盖的分布规律是一致的，但在不同基因型之间存在差异。在 B. peruviana 的基因型中观察到具有光滑网状嵴的花粉，而在 B. glabra 和 B. spectabilis 的基因型中发现了覆盖嵴的花粉。每种九重葛种质的花粉粒直径范围很广。二倍体基因型花粉粒平均直径为22.2~32.1 μm，多倍体基因型花粉粒平均直径为26.7~40.4 μm。在二倍体和四倍体基因型中观察到发芽的花粉粒，其花粉发芽率一般小于20%。发芽的花粉粒的大小明显大于沉默的花粉粒，说明粒大小分布不均匀是九重葛花粉发芽能力低的重要原因。在二倍体和四倍体基因型中观察到发芽的花粉粒，其花粉发芽率一般小于20%。发芽的花粉粒的大小明显大于沉默的花粉粒，说明粒大小分布不均匀是九重葛花粉发芽能力低的重要原因。在二倍体和四倍体基因型中观察到发芽的花粉粒，其花粉发芽率一般小于20%。发芽的花粉粒的大小明显大于沉默的花粉粒，说明粒大小分布不均匀是九重葛花粉发芽能力低的重要原因。