Germination and dormancy of Arthropodium cirratum seeds

Seed dormancy characteristics and environmental limitations on seed germination in Arthropodium cirratum (Forst, f.) R. Br. are related to seed propagation in nature. A natural population and a cultivated population show identical responses, except that a secondary dormancy can be induced in seed of the natural population after storage for at least 9 months. A period of 3-6 months of after-ripening is required after initiation of seed dispersal to alleviate an innate seed dormancy. This seed dormancy can be attributed to the balance between the 'expansive force' of the embryo and the 'mechanical constraint' of the seed coat. Seed germination occurs over a wide range of environmental conditions. It is more rapid at temperatures of 12-25°C, in darkness or low light intensity, and high water potential. However, many seeds eventually germinate at temperatures from 5-30°C, under high light (295 μmol m^-2 sec^-1 ) or very low water potential (1.5 mPa). Seed stratification at 2°C for at least 3 weeks induces a secondary dormancy. A novel observation includes the inhibitory effect of diurnal alternating temperatures on germination.