Freshly-matured seeds of Vaccinium myrtillus, V. vitis-idaea and V. uliginosum from coniferous forests in Sweden were tested for germination in light and darkness at 12/12 h daily temperature regimes at 15/5 (or 15/6), 20/10 and 25/15 C. Seeds also were tested at the same conditions after they were cold stratified. In initial tests, seeds of V. myrtillus and V. vitis-idaea germinated to 62-100% in light at 20/10 and/or 25/15 C with few (1-12%), or no seeds germinating at 15/5(6) C; however, after 12 or 20 wk of stratification germination percentages increased significantly in light at 15/5(6) C. Thus, seeds of these species are conditionally dormant at maturity. One to 20% of V. myrtillus and 0-2% of V. vitis-idaea seeds sown outdoors in southern Sweden on various dates in summer germinated before winter. Seeds of neither species germinated during late May, when minimum temperatures were about 7-10 C, but they germinated after minimum temperatures increased to ³ 10 C. Stratified seeds of V. myrtillus and V. vitis-idaea required more than 2 wk of incubation at 15/5(6) C for initiation of germination. Therefore, even after habitat temperatures have reached the minimum range for germination of nondormant seeds, a slow rate of germination at low temperatures may prevent them from germinating in early spring. Nonstratified seeds of V. uliginosum germinated to a maximum of 5% in light and of 7% in darkness, but after 12 wk of stratification seeds germinated to 49-95% in light and to 1-60% in darkness at 15/5, 20/10 and 25/15 C. Most seeds of V. uliginosum were dormant at maturity, and they came out of dormancy during stratification in winter. Seeds of V. uliginosum germinated over the same range of temperatures as those of V. myrtillus and V. vitis-idaea by spring, but they germinated faster at 15/5(6) C than those of the other two species.

Key words: blueberry seed germination, cold stratification, Ericaceae, seed dormancy, seed germination, Vaccinium