Variation in seed dormancy of the wetland sedge, Carex elongata, between populations and individuals in two consecutive years

Variation in dormancy of the wetland sedge, Carex elongata L., was tested using seeds from three wild populations and the garden-grown progeny of one population. Germination experiments, comprising four combinations of temperature and light, were conducted either with fresh-matured or cold-stratified seeds, to assess the relative contribution of populations and mother plants to the total variation. Between-year variation was tested at the population level and, partly, at the individual level, using seeds collected in two consecutive years. Among-population variation accounted for 72%, and among-individual variation for 23%, of the total variance in the first experiment. Significant differences were apparent between one wild population and its garden-grown descendants. Differences in germinability among populations were maintained in the two consecutive years, but a proportion of the variance was due to the contribution of the maternal environment. Weak evidence for genetic control at the individual level was shown by a correlation across years in one population. However, the lack of a main effect at the individual level in the first experiment makes it difficult to assess the relative contribution of the mother plants to the total variation. Our results imply that germination patterns of C. elongata have a genetic basis, but are markedly modified by environmental conditions.