Relationship of pear pollen and stigma development with temperature

The effect of temperature on pear flower development is a prerequisite for using bees in pear pollination. In this study, the main varieties of Pyrus bretschneideri cv. 'Dangshansuli' and P. bretschneideri cv. 'Yali' served as pollination test materials. Three temperatures (8 ℃, 12 ℃ and 20 ℃) were set to explore the dynamic blossoming and stigma receptivity of 'Dangshansuli', and pollen release, pollen germination, pollen tube growth of 'Yali', and other indicators to lay the theoretical basis for the reasonable use of bee pollination of pears. The results showed that at 8 ℃, the required time for flower opening of 'Dangshansuli' exceeded 144 h. Also the time for stigma receptivity delayed to 112 h and that for pollination persistence shortened. The time for pollen release of 'Yali' extended to 230 h. Pollen germination rate at 8 ℃ was less than that at 20 ℃ (P< 0.05). After culturing for 96 h, the number of pollen tubes arriving at the top, middle and base of styles of 'Dangshansuli' was respectively 84, 55 and 43. At 12 ℃, the time for flower opening of 'Dangshansuli' was 114 h, and strong stigma receptivity occurred 88 h later. The time for total pollen release of 'Yali' was 158 h. While pollen germination at 12 ℃ was faster than that at 8 ℃, the pollen germination rate was significantly lower than that at 20 ℃ (P < 0.05). After culturing for 96 h, the number of pollen tubes arriving at the top, middle and base of styles of 'Dangshansuli' was respectively 111, 105 and 92. When temperature was 20 ℃, the required time for the blossoming of 'Dangshansuli' was 44 h. Stigma receptivity was strong and pollination persistence time reached 120 h. The required time for total pollen release of 'Yali' was 64 h and pollen germination rate was high. After culturing for 96 h, the number pollen tubes arriving at the top, middle and base of styles of 'Dangshansuli' was respectively 121, 120 and 119. The temperature of 20 ℃ was more suitable for pear growth and pollination by bees than 12 ℃ and 8 ℃. The present study laid the scientific basis for future studies on biological characteristics of pear blossoming at different temperatures. It also laid the foundation for practical application of honeybee pollination technology in pear farms.