Factors Controlling Fruit Set of ‘Napoleon’ Sweet Cherry in Western Oregon

Abstract

During 1982–84, pollen tube growth rate in styles of ‘Napoleon’ sweet cherry ( Prunus avium L.) was related to genotype and temperature. At temperatures of 7.3° and 9.9°C, ‘Corum’ pollen tube growth was the slowest, ‘Bada’ the fastest. Maximum stigma receptivity of ‘Napoleon’ occurred for 5 days after anthesis at 9.4°. Ovules were functional for at least 13 days after anthesis. Hand pollination of ‘Napoleon’ resulted in a high fruit set irrespective of pollinizer source or weather conditions during the 3 years. Open pollination developed adequate fruit set for a commercial yield in all 3 years, although it was variable, 24% to 50%. Data in 1984 suggest that insect pollinators were active below 13°.