Studies on dormancy, germination, and survival of seeds buried in soil of the rare plant species Aeschynomene virginica (Fabaceae)

Dormancy in seeds of Aeschynomene virginica is caused by a water-impermeable ("hard") seed coat. In the laboratory, dormancy was broken by mechanical scarification, dry heat, wet heat (boiling), dry storage, incubation on a moist substrate for several months, and (to a lesser extent) freezing. Wetting/drying cycles were ineffective in breaking dormancy. Nondormant seeds germinated over a wide range of temperatures in both white light and darkness, in far-red light, at salinities (NaCl, Na ₂SO ₄, MgSO ₄) of 0-1%, and while flooded or buried in soil. Fewer seedlings emerged from nondormant seeds buried > 3 cm in soil than from those buried 1 or 2 cm; emergence was 93% at 1 cm and 19% at 5 cm. Germination of only a few of the dormant seeds sown on the soil surface in a nonheated greenhouse in autumn 1995 was delayed until spring 1997, while 44% of those buried 7 cm deep in soil were still dormant ("hard") in spring 1999. Thus, it seems likely that A. virginica has the potential to form a persistent seed bank in its natural habitat.