Pollen Morphological Characteristics of Ornamental Crabapples

Abstract

In order to understand the basic characteristics of Malus pollen, 107 Malus germplasm pollen samples were observed by a field-emission scanning electron microscope. The results showed that: Malus pollens belonged to the N₃P₄C₅ type, were all bilaterally symmetrical, with perprolate, prolate, or sub-rectangular shapes in equatorial view, and tricolpate with three germinal furrows in polar view. Each furrow extended to the two poles along the polar axis and they did not cross each other. Striate ornamentation was mostly present in the pollen exines, with most contained perforations. Pollen shape and size have a higher stability (variation coefficient<15%), especially in the direction of the equatorial axis (variation coefficient<7%), whereas exines ornamentation was not that much stable, especially pollen perforation density (variation coefficient = 68.9%). The pollen of the species and cultivars was consistent with the stability of morphology, size, and exines ornamentation.