THE EFFECT OF TEMPERATURE ON POLLEN GERMINATION AND POLLEN TUBE GROWTH OF SOUR CHERRY CULTIVARS

The study was carried out to determine the effect of three different temperatures (5, 15 and 25°C) on in vitro pollen germination and pollen tube growth of five sour cherry cultivars: ‘Heimanns Konservenweichsel’, ‘Kelleriis 14’, ‘Oblačinska’, ‘Rexelle’ and ‘Šumadinka’. Pollen germination was determined by germinating pollen grains in a culture medium containing 0.7% agar-agar and 15% sucrose. Temperature significantly affected pollen germination. High germination rates (50–70%) were obtained at both 15°C and 25°C. Satisfactory germination rates (42–51%) were also obtained at 5°C in some cultivars (‘Rexelle’, ‘Šumadinka’ and ‘Heimanns Konservenweichsel’). The influence of temperature on the pollen tube growth was more prominent. The length of pollen tubes was three to six times higher at 15°C and 25°C in comparison with 5°C. This has led to the conclusion that the temperature of 5°C, although it could be adequate for pollen germination, is not high enough for optimal pollen tube growth.