germination: one construct, many systems

In plant biology germination is the resumption of active growth by a quiescent seed: water uptake (imbibition) reactivates metabolism, stored reserves are mobilised, and the process culminates in the radicle emerging through the seed coat, ending dormancy. Bewley's Seed germination and dormancy sets out the stages and the hormonal balance that decides whether and when a seed germinates. The referent is a dormant propagule switching back on and committing to grow, the same event the maltster harnesses and the microbiologist sees in spores.[1]

Unit

The proportion of seeds that emerge, and the time to emergence

Recovery means

Not applicable

Measured by

Scored by germination percentage, mean germination time, and radicle emergence

Microbiologists use germination for the parallel event in spores: a dormant, highly resistant bacterial endospore senses specific nutrient germinants, rapidly rehydrates and sheds its protective layers, and returns to a growing vegetative cell. Setlow's Spore germination traces the receptors and the loss of dormancy that commit a spore to outgrowth. It is the same dormant-to-active transition as in a seed or a malting grain, realised in a single-celled system.[2]

Unit

The proportion of spores that exit dormancy over time

Recovery means

Not applicable

Measured by

Followed by loss of refractility, release of dipicolinic acid, and the drop in optical density