Pregermination

Pregermination is a term used in seed biology to describe the early physiological and biochemical phase that follows water uptake by a seed and precedes visible germination, such as radicle emergence. It encompasses the period when metabolic processes are activated but growth has not yet produced an observable germ shoot or root.

During pregermination, imbibed seeds resume respiration and undertake extensive cellular repair and maintenance. Enzymes are synthesized to mobilize stored reserves (such as starch, oils, and proteins), and energy production ramps up to support further growth. Nucleic acids are repaired or synthesized, membranes are reconstituted, and protective systems are reinforced to withstand environmental stress. This phase prepares the embryo for the rapid growth that occurs during germination.

The duration and character of pregermination depend on species and environmental conditions, including moisture, temperature, and oxygen availability. Some seeds can complete pregermination quickly under favorable conditions, while others may require extended periods or dormancy-breaking cues such as stratification or scarification. Seed priming, a controlled pre-germination treatment involving partial hydration followed by drying, intentionally manipulates this phase to improve germination speed and uniformity.

Pregermination is distinct from germination proper, which is defined by the physical emergence of the radicle or shoot. In practical terms, the pregermination phase is medically and agriculturally relevant for seed vigor assessments and for techniques like priming, which aim to optimize the subsequent germination process and crop establishment.