Germination requirements of the alpine endemic Silene elisabethae Jan: effects of cold stratification, light and GA₃

Silene elisabethae Jan (Caryophyllaceae) is a narrow endemic plant species that occurs in calcareous grasslands of the Southern Italian Alps, and is protected by National and Regional Red Lists (IUCN). Seed germination requirements of this species were studied for the first time with the aim of producing appropriate germination protocols for use in ex situ conservation. Seeds were collected from three populations and sown on agar in the laboratory. Increasing durations of cold stratification resulted in an increase in germination from 20 to 90%. In addition, GA₃ could substitute for a cold stratification requirement resulting in 90 to 100% germination in the absence of chilling. All populations germinated to higher levels in the light than dark, and populations from the coldest collection site germinated better at low temperatures, suggesting adaptation of seed germination behaviour to the local microclimate. Our results indicate that seeds of S. elisabethae exhibit non-deep physiological dormancy and that light plays an important role as a germination cue.