POLLEN-TUBE GROWTH IN SOUR CHERRY (PRUNUS-CERASUS L) AT DIFFERENT TEMPERATURES

Studies were conducted on the germination on sucrose-agar of pollen of Cacanski Rubin, Heimanns Konservenweichsel and Sumadinka and on pollen tube growth of these three cultivars in the pistils of "Cacanski Rubin'. Pollen tube growth in the pistils was recorded at 5, 10, 15, 20, and 25-degrees-C. The highest average number of pollen tubes in the style and ovary, and to some extent the percentage of pistils in which the pollen tubes reached the nucellus, was assessed in all three combinations of pollination at the optimum temperatures of 15 and 20-degrees-C. 'Sumadinka' had the highest percentage of germinated pollen grains on the artificial medium in both years studied, as well as the highest average number of pollen tubes in the style and ovary of 'Cacanski Rubin' and the greatest percentage of pistils in which the pollen tubes reached the nucellus of 'Cacanski Rubin'. The occurrence of incompatibility observed in the upper third of the style was most pronounced in the combination of self-pollination at 5-degrees-C in one of the years.