Betula pendula seed storage and sowing pre-treatment: effect on germination and seedling emergence in container cultivation

Irregular seed crop in Betula pendula (Silver Birch) is a reason to create seed reserves, ensuring nursery production in years of crop failure. This study investigated the effects of seed moisture content and storage temperature on germinability and seedling emergence in container cultivation. Mature catkins were collected separately from 3 trees. The mixture of winged nuts and scales was dried to 3 levels of moisture content and stored at 3°C, –3°C and –10°C. After storage for 3, 5 and 6 years, the seeds were separated from scales and next dewinged and sorted in acetone into empty and filled seeds. Cleaned nuts were germinated in the Jacobsen germinator. Besides, to assess seedling emergence, seeds were sown on the surface of peat mixed with perlite, in multi-cell trays under a plastic tunnel. Significant differences in germinability were detected depending on the mother tree, seed moisture content and storage time. The viability of seeds stored at –10°C remained unchanged for 6 years regardless of moisture content (ca. 8–12%). Seeds stored at higher temperatures lost their germinability faster. An unexplained increase in seedling emergence was observed after extended seed storage at –10°C, in contrast to a gradual decrease in seedling emergence after extended storage at –3°C.