Effect of Temperature on Pollen Germination, Pollen Tube Growth, Effective Pollination Period, and Fruit Set of Pear

Fruit setting factors of Pyrus communis L. , ‘Tsakoniki’ pear, were observed under field and controlled environmental conditions during 1980—83. Pollen germination of ‘Tsakoniki’ and ‘Coscia’ was reduced at temperatures below 15°C whereas pollen tube growth rate in vitro and in vivo increased with temperatures between 5° and 25°C. Pollen tube growth in selfed styles of ‘Tsakoniki’ at all temperatures tested was slower than in crossed ones and pollen tubes reached the base only in 10% to 20% of the styles. Effective pollination period (EPP) was prolonged at low temperature and ranged between 3 and 13 days under various temperature treatments. Fruit set of ‘Tsakoniki’ was limited chiefly by pollen transfer and to a lesser extent by poor pollen tube growth at low temperature.