Abstract
To improve the fruit set of sweet cherries, we investigated the effects of an acclimation method of pollen storage on the fruit bearing rate and pollen activity. Pollen stored at a low temperature, −30°C, led to a 14.0% germination rate immediately after being transferred from the freezer. When acclimated for 2 hours at relative humidity 90%, the germination rate rose significantly to 42.4%. By increasing the acclimation period to 4 hours, the germination rate did not change significantly at 45.9%. Under dry conditions of relative humidity 30% and an acclimation period within 4 hours, there was no significant difference in the pollen germination rate. Examination of the effect of the acclimation temperature on the pollen germination rate under relative humidity 90% for 2 hours showed little difference in the germination rates (43.0% at 4°C, 45.4% at 20°C). However, when pollen was acclimated for 12 hours at 25°C, the germination rate was significantly reduced to 7.9%. Artificial pollination using stored pollen that had been acclimated with the conventional method led to a fruit bearing rate of 2.5%. The fruit bearing rate was 17.2% with artificial pollination when stored pollen was acclimated for 2 hours at a high humidity (90%RH). Further more, the fruit bearing rate on artificial pollination with pollen acclimated under high humidity conditions was higher than when using pollen acclimated under dry conditions or using conventional methods.
