Intraspecific variation in pollen viability, germination and ultrastructure of Olea europaea L.
Variability of pollen morphology and ultrastructure of Olea europaea L. (Oleaceae) cultivars ‘Koroneiki’, ‘Mastoidis’ and ‘Kalamata’ was studied with scanning electron microscopy to identify genotype- distinguishing characters that could be employed for morphological cultivar discrimination. Pollen viability and germination was also measured for the three cultivars. Significant variation was observed in minimum diameter, maximum/minimum diameter (L/W) ratio and size index of pollen grain of ‘Mastoidis’ and the other two cultivars. Regarding the exine pattern, muri width of ‘Koroneiki’ and ‘Mastoidis’ pollen was similar and significantly lower than that of ‘Kalamata’. The highest values of maximum diameter were observed in ‘Kalamata’ and differed significantly with ‘Mastoidis’ but not with ‘Koroneiki’. No marked variation was noted in minimum diameter and L/W ratio. ‘Kalamata’ was characterized by higher size index than the other two cultivars, though statistical difference was observed only when compared with ‘Mastoidis’. Higher pollen viability and in vitro germination was recorded for ‘Kalamata’ and ‘Mastoidis’ compared to ‘Koroneiki’. Acquired information could contribute to the establishment of a database for future olive germplasm classification studies.
Keywords: Floral biology, olive, pollen ultrastructure, scanning electron microscopy