Germination and dormancy of Sida hermaphrodita seeds

Sida hermaphrodita seeds produced at two locations in multiple years were investigated for germination and dormancy, including the morphological mechanisms responsible for physical dormancy and changes in the seed coat induced by imbibition and chemical scarification. The imbibing capacity of S. hermaphrodita seeds immediately after harvest and after one year of storage was high (from 0.69 to 1.08 g H2O g(-1) seeds), but varied between years and decreased over time. Seed conditioning and the separation of the heavy seed fraction increased germination to more than 77%. Each lot of heavy seeds (which sank in water) produced germinated seeds, imbibed non-germinated seeds and hard seeds. The proportion of hard seeds in each batch varied widely between years and locations. An analysis of the morphological and anatomical characteristics of S. hermaphrodita seeds revealed structures responsible for water absorption. Scarification for 30 minutes with 95% sulphuric acid was most effective in breaking the physical dormancy of seeds (compared with longer periods of scarification) resulting in imbibition without impairing embryo viability.