SEM Observations, Pollen Viability and Germination in Some Selected Plum Genotypes Cultivated in Romania

The pollen morphology, viability, germination and pollen tube growth of six wide-spread plum genotypes (Prunus domestica), were studied. 'Toptaste', 'Topfive' and 'Gras ameliorat' had the largest pollen grains (> 50 mu m), whereas 'Jojo', 'Anna Spath' and 'Stanley' cultivars were represented by slightly smaller pollen size (45.28 - 48.41 mu m). Pollen shape was prolate-sheroidal (L/W ratio 1.18-1.02 mu m) in the polar view and spherical-triangular in the equatorial view. Pollen viability varied with the genotype: the highest percentage was observed for 'Jojo' (40.96%) and ' Toptaste' (40.87%), the lowest was recorded for ' Gras ameliorat' (26.33%). The highest pollen germination (87.0%) at the end of 24 h incubation at 10 degrees C was recorded for 'Stanley'. 'Anna Spth' developed the longest pollen tubes (1061.1 mu m) when the pollen grains were incubated at 15 degrees C for 24 h.