afterripen

Afterripening is a seed dormancy-release process that occurs during dry storage after the seed has matured. In seeds with physiological dormancy, germination is suppressed at harvest but becomes possible after a period of storage in dry conditions. Afterripening is distinct from stratification, which requires moist chilling or other moist conditions to break dormancy, and from scarification, which physically damages the seed coat to permit germination.

The rate and occurrence of afterripening depend on the species, the level of dormancy, and storage conditions such as temperature, humidity, and duration. It often takes weeks to months of dry storage at ambient or moderately warm temperatures for dormancy to be released, but some species require longer or shorter periods. Afterripening can occur even when seeds are fully dry and not imbibed.

Biochemically, afterripening is associated with changes in embryo physiology and hormonal balance, including reduced sensitivity to abscisic acid and/or altered gibberellin signaling, as well as metabolic and membrane changes. The exact mechanisms are not fully understood and may vary among species.

From an applied perspective, afterripening helps explain variation in germination timing and vigor in stored seed, informs seed storage guidelines, and influences seed-testing protocols. It is also a consideration in ecology and conservation, where the timing of germination affects establishment and survival.