Non-deep physiological dormancy and changes in germination during cold dry storage of two subalpine <i>Primula species</i> endemic to southwest China

Newly-harvested seeds of Primula efarinosa and P . nutantiflora germinated to 0‐39% at seven temperatures in light, indicating that about 40% of the seeds were non-dormant. However, seeds treated with 100 and 200 μM GA3 germinated to 83‐87% at 25°C and 25/15°C, but not at the other temperatures, implying that the promoting effect of GA3 on germination of these two species was highly dependent on incubation temperature. Seeds were released from dormancy by cold stratification at 2°C, and germination of seeds of both primroses germinated to &gt; 80% after 12 months of cold stratification. Germination of cold-dry-stored seeds increased in the first six months, which may be due to after-ripening, and then decreased to about 50% in the 12th month of cold-dry storage. Taken together, seeds of both species have non-deep physiological dormancy at maturity and after dormancy-break, they require light and temperatures of about 25°C to germinate. Moreover, an excessive after-ripening treatment decreased seed germination/viability of both species.