Studies on Pollen Morphology and Characteristics of Dictamnus dasycarpus

Dictamnus dasycarpus is an important wildflower resource in Hebei Province. Its colorful and attractively shaped flowers possess high ornamental value. In this study, D. dasycarpus from the Baoding region was used as experimental material. Scanning electron microscopy was employed to observe pollen morphology, and four staining methods were used to assess pollen viability and changes in viability under different storage conditions (25 ℃, −4 ℃, −20 ℃, −80 ℃). Additionally, fluorescence microscopy was used to observe the pollen germination process, exploring the morphology and germination characteristics of D. dasycarpus pollen. The results indicate that the pollen of D. dasycarpus is oblong, with three germination furrows extending to two levels and a three-lobed circular shape at the pole. The MTT method, carmine acetate, and the I₂-KI method all effectively stained the pollen. In the MTT method, viable pollen appeared bluish-purple, while non-viable pollen was colorless, allowing clear color differentiation. Pollen staining changed significantly over time. Under carmine acetate and I₂-KI staining, there was no significant change in pollen staining between 1 and 3 days after flowering, while the 2,3,5-triphenyltetrazolium chloride (TTC) method failed to stain pollen at any time point. Pollen stored at −80 ℃ for 60 days exhibited a viability of 45.47%, indicating an extended lifespan. In cross-pollination experiments, pollen germinated on the stigma surface 2 hours after pollination, and a small number of pollen tubes began entering the ovary 48 hours after pollination. In summary, the findings of this study enhance our understanding of the morphology and characteristics of D. dasycarpus pollen and provide a reference for further research.