Seed Germination of Raspberry (Rubus idaeus L.) Depending on the Age of Seeds and Hybridization Partners

Research was carried out on the germination of seeds obtained from crossings between the cultivars of red raspberry (Rubus idaeus L.) ‘Sokolica’, ‘Willamette’, ‘Veten’, ‘Canby’ and ‘Glen Ample’ depending on the age of the seeds. The crossings were performed in the winter–spring of 2015–2018 in a heated greenhouse. The obtained seeds were stored dry in paper bags at a temperature of 4–5 °C. In January 2019, seeds were scarified and then cold stratified for 50 days and seeded in pots in a greenhouse. The seedling emergence was assessed 60 days after sowing. The seeds produced in 2015 had the lowest germination percentage (14% on average for all combinations of crosses), while the seeds produced in 2018 had a germination rate of 44.9%. Significant differences were also observed in the emergence of seedlings from different combinations. On average, the fewest seedlings were obtained from the combination ‘Glen Ample’ × ‘Willamette’ and the most from ‘Sokolica’ × ‘Willamette’.