Dormancy, germination requirements and storage behaviour of seeds ofConvolvulaceae(Solanales) and evolutionary considerations

Abstract

AbstractConvolvulaceaeis the only family in the asterid clade with species that produce physically dormant seeds, and most studies on germination in this family have focused on scarified seeds. However, no study has been done on the taxonomic/evolutionary pattern of seed dormancy inConvolvulaceae. We determined the moisture content of non-treated seeds and water uptake and germination percentages for non-treated and manually scarified seeds of 46 species in 11 of the 12 tribes in this family. Germination was tested over a range of temperatures in light/dark and in the dark. The effect of drying and storage at low temperatures was tested on seeds ofErycibe henryiandMaripa panamensis, the only species with high initial moisture content. Non-treated fresh seeds ofBonamia menziesii,M. panamensisandE. henryiimbibed water, whereas those of the other 43 species did not. Manually scarified seeds of all these 43 species took up large amounts of water. Therefore, seeds of 43 of the 46 species are physically dormant, and three are non-dormant. Seeds of all 46 species germinated after imbibition, except those ofCuscuta europaea, which are reported to have combinational dormancy.M. panamensisandE. henryiseeds are recalcitrant and those of the other 44 species orthodox. InConvolvulaceae, basal tribes or tribes derived from basal tribes contain species with non-dormant recalcitrant, physically dormant orthodox and combinationally dormant orthodox seeds. Physical dormancy of seeds in this family possibly evolved from a non-dormant recalcitrant seed-producing ancestor closely related toErycibeae.