Yasamin Shamsolshoara - Department of Horticulture, Karaj Branch, Islamic Azad University, Karaj, Iran
Rahim Gharesheikhbayat - Temperate Fruits Research Center, Horticultural Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Seied Mehdi Miri - Department of Horticulture, Karaj Branch, Islamic Azad University, Karaj, Iran
Mohiedin Pirkhezri - Temperate Fruits Research Center, Horticultural Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Daryoush Davoodi - Department of Nanotechnology, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

The occurrence of inter-specific hybrids between two species in nature has the potential ability to develop new fruit trees with desirable traits. In this study, flower morphology, viability, and in vitro germination of pollen grains and self-(in) compatibility, using fruit set (%) and fluorescence microscopy methods were examined in three promising natural Prunus interspecific hybrids [P. armeniaca × P. salicina (Bavanat) and P. cerasifera × P. armeniaca (Shiraz and Shahriar)]. Bavanat and Shiraz had the highest flower diameter, while the highest number and length of stamens, as well as stamen number/pistil length ratio, belonged to Shahriar. The highest and lowest pollen viability and in vitro germination were observed in Shahriar and Bavanat, respectively. In general, sucrose concentrations of ۱۵۰ to ۲۵۰ g/l increased in vitro pollen germination rate, although concentrations of more than ۱۵۰ g/l had a negative effect on Bavanat. The three-year average (۲۰۱۸-۲۰۲۰) of final fruit set by self-pollination ranged from ۰% in Shiraz to ۱.۳% in Shahriar. A strong positive correlation was found between the occurrence of twin pistils and the mean temperature from July-August in the previous year. According to field self-pollination and fluorescent microscopy, all three genotypes were considered self-incompatible and needed pollinizer varieties.

Fluorescent microscopy, Fruit set, Inter-specific hybrid, In vitro germination, Pollen viability