S02 - Session P6 - Ovule senescence in the ovary of autochthonous sweet cherry Balkans genotypes as affected by pistilar genotype and temperature

Authors: Nebojsa Milosevic *, Sanja Radi269evi263, Melpomena Popovska, Milena 272or273evi263, Radosav Cerovi263, Sla273ana Mari263, Viktor Gjamovski

The reproductive phase of flowering is one of the most sensitive stages to temperature stress that has a detrimental effect on fruit sets. Higher flowering temperature accelerates ovule senescence, leading to female gametophyte degeneration and ovule abortion. The sweet cherry ( Prunus avium L.) is generally considered better adapted to the conditions of colder climates. For this economically important species, genetic diversity is crucial in adapting to actual changes in environmental conditions. The genotypes showing temperature tolerance are potential sources of relevant genes. This study was carried out to investigate ovule senescence of two late flowering sweet cherry landraces of Balkan origin ('Ohridska Crna ̓ and 'Dolga Šiška ̓) under the conditions of a prevailing Mediterranean climate in the Ohrid Lake (Republic of North Macedonia). Monitoring was performed using the fluorescence microscopy method on emasculated pollinated flowers (cross-pollination) and non-emasculated open-pollinated flowers (open pollination) in three terms of pistil fixation (3 rd , 6 th and 10 th day from the full flowering date). The appearance of fluorescence as an indicator of ovule senescence was more pronounced in the ovaries of 'Dolga Šiška' (43.16%; 51.29%; 62.63% by fixation terms, respectively) compared to 'Ohridska Crna ̓ (14.67%; 26.67%; 40.00%, respectively) in cross-pollination variant. The percentages of fertilization and fruit set considered from the aspect of landraces' behaviour as pollinated pointed to complex dependence on the temperature and emasculation. The results revealed a high ovule vitality of 'Ohridska Crna ̓ even on the 10 th day after full flowering. Further investigations at the histological level will confirm/deny its superior female reproductive behaviour regarding higher flowering temperatures. Such an approach can lead to the target use of the well-adapted and high-quality fruited landraces for obtaining new cherry cultivars, which can withstand global warming during the reproductive stage.