The effect of genotype-temperature interaction on pollen performance in the pistils of autochthonous ‘Dolga Šiška’ sweet cherry

Abstract

Within sweet cherry (Prunus avium L.), diversity is of the crucial importance in the context of adaptation to changing environmental conditions. The cultivars origin, their wider geographical distribution or spatial limitations in certain regions are related to their requirements for adequate conditions, which is especially visible through the reproductive process. This study was carried out to investigate pollen performance in vivo in the pistils of sweet cherry landrace of Balkan origin (‘Dolga Šiška’) over two-year period, in the conditions of prevailing Mediterranean climate of Ohrid Lake vicinity (Republic of North Macedonia). The pollenisers used are also of indigenous origin – ‘Ohridska Crna’ (Balkan region) and ‘Kordia’ (Czech Republic). Investigation was performed using the fluorescence microscopy method, on emasculated hand-pollinated flowers (cross-pollination) and non-emasculated open-pollinated flowers (open pollination), in three terms of pistil fixation (3rd, 6th and 10th day from the full flowering date). In general, ‘Ohridska Crna’ showed a tendency of inducing higher number of pollen tubes (22.14, 11.78 and 6.20 pollen tubes in the upper, middle and lower part of the style, respectively) in comparison with ‘Kordia’ (12.72, 6.62 and 2.92, respectively). This effect was particularly pronounced in the year with higher flowering temperature. On the other hand, pollen tube kinetics showed the opposite tendency, being better with ‘Kordia’ as polleniser in colder flowering season (7.69% of fertilization percentage and 3.60% fruit set, respectively), in comparison with ‘Ohridska Crna’ (penetration of pollen tubes into the nucellus and fruit set were not observed). Analysis of pollen performance in vivo parameters, pointed to the complex dependence on the polleniser genotype and temperature before and during the flowering, as well as the influence of pollination mode and pistilar genotype, which together contribute to the main factors’ interaction.