Physical dormancy alleviation at room temperature storage is influenced by the initial moisture content of the seeds

Abstract

In seeds with impermeable coats, i.e., physical dormancy (PY), dormancy break may occur at room temperature during ex-situ storage or when seeds experiencing similar conditions when buried in the soil. Here, we tested the influence of initial seed moisture content and storage on dormancy break in the seeds of Adenanthera pavonina, Bauhinia racemosa, Cassia fistula, Dodonaea viscosa, and Delonix regia. Drying results in most seeds of these species becoming water-impermeable. We arbitrarily chose two moisture ranges, shallow (impermeable, high moisture content) and absolute (impermeable, low moisture content) PY, and stored the seeds at room temperature for 8.5 years. The moisture content at which the permeable to impermeable transition occurred and the range constituting shallow and absolute PY varied between species. Across species, the shallow PY group had a significantly higher number of nondormant seeds at the end of storage, whereas the absolute PY group did not show any germination, except c. 20% germination in A. pavonina and C. fistula. Thus, PY break in seeds stored at room temperature may occur after several years, but this largely depends on the initial seed moisture content.