Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 18, 2005
Publication Date: July 18, 2005
Citation: Foley, M.E. 2005. What is afterripening?. [Abstract]. American Society for Horticultural Sciences. 40(4):956.
Interpretive Summary: Seed dormancy is the temporary failure of a mature, viable seed to germinate under favorable conditions within a specified period of time. To overcome dormancy in nature, seeds must be exposed for a period of time to specific environmental conditions, which depend on the species and the depth of seed dormancy. The general term to describe processes and changes in dormant seeds that lead to a less or non-dormant state is afterripening. Mechanisms and signals that regulate afterripening have been investigated, but remain unknown.
Afterripening is a catch-all term to denote processes, interactions, and changes associated with transition of dormant seeds to a non-dormant or fully afterripened state. More precisely, afterripening is the loss of the dormant state, over some period of time, through exposure of the seeds to a set of environmental conditions after maturation and separation from the parent plant. Environmental conditions in nature that facilitate afterripening vary with species. For example, some species respond to warm, dry conditions; some to cool, moist conditions (i.e., stratification or chilling); and some to both sets of conditions. The period of time required to fully afterripen seeds is governed by the species, depth of dormancy in the population, and the degree of each environmental factor applied. Afterripening does not bring about an abrupt change from a dormant to a fully germinable state. Rather, seeds in a population become more responsive to a range of conditions at which they are able to germinate and less responsive to conditions that restrict germination. The amount of afterripening seeds have undergone is determined by comparing time to the onset of germination and rate of germination in dormant versus afterripened seeds from the same population germinated under the same conditions. Afterripening remains a 'black-box'. In known and unknown ways, afterripening integrates internal and external factors for development to achieve a threshold for germination. A great deal of fundamental research on representative species aimed at revealing mechanisms and signaling pathways for dormancy, afterripening, and early germination will be required to precisely answer the question: What is afterripening?