In vitro Pollen Germination and Pollen Tube Length as Indicators of Temperature Effects on Sweet Cherry Genotypes

This study evaluated the effects of temperature on in vitro pollen germination and pollen tube growth in eight sweet cherry genotypes (‘Burlat’, ‘Canetova’, ‘Dolga Šiška’, ‘G-2’, ‘Kordia’, ‘Lapins’, ‘Rita’, and ‘Sunburst’) over two consecutive years (2022–2023). Experiments were conducted at 17°C and 20°C to assess genotypic variability and adaptability under changing climatic conditions. Results revealed considerable variability among genotypes: pollen germination ranged from 9.3% (‘Kordia’) to 53.9% (‘Lapins’), while pollen tube length varied from 180.8 µm (‘Dolga Šiška’) to 669.3 µm (‘Lapins’). Germination was generally higher at 17°C than at 20°C, contrary to expectations. ‘Lapins’, ‘Canetova’, and ‘G-2’ maintained stable pollen germination and tube growth across years, highlighting their potential as reliable pollenisers. In contrast, ‘Dolga Šiška’ and ‘Sunburst’ showed drastic reductions under less favourable conditions, confirming their sensitivity to environmental stress. Analysis of variance indicated that genotype was the dominant factor for pollen tube growth, while strong genotype × year interaction was the main determinant of pollen germination. These findings demonstrate that pollen performance is a valuable indicator of reproductive resilience, and they identify genotypes suitable for orchard planning to secure fruit set and yield stability under climate change.