Characterization of the Germination Responses of Silene dioica (L.) Clairv., Populations from Europe

Germination tests were done on 20 populations of Silene dioicacollected in different parts of Europe. Seeds collected fromwild plants and from their progeny growing at R.B.G. Kew, weretested using both freshly harvested and stored seeds. Responseswere compared from tests done on thermo-gradient bars and inincubators to examine germination and after-ripening processesbetween c. 2-c. 45 °C. The responses of different populations were characterized byidentifying variations due to the proportions of dormant seeds,the maximum and minimum temperatures favouring germination,and the time course of germination at particular temperaturesof freshly shed and stored seed. Germination and after-ripeningresponses of different populations displayed marked qualitativesimilarities, but differences in the degree of their expressionresulted in statistically significant quantitative differenceswhich could sometimes be correlated with features of the geographicaldistribution of the populations. The results are discussed in relation to the occurrence of thisspecies in a well-defined natural habitat in Europe, and itis concluded that they represent a situation in which fundamentallysimilar control patterns underlying the responses of every populationexamined are modulated quantitatively to produce variationsin the number of seeds germinating at particular seasons orremaining dormant within the soil.