Theory 085/Food & Agriculture /Seed science
Germination Is a Rate, Not a Total
Sowing advice targets moisture. The seed may be measuring how fast water arrives.
Germination is triggered by the rate of water uptake rather than by the total water available, so seeds on a wet substrate that delivers water slowly may fail where a drier substrate delivering quickly succeeds.
01The evidence
Germination varies between substrates at equal water content, and the variation tracks the rate of imbibition rather than the final moisture.
02The tension
Germination models use moisture content and temperature, which predict from the total available and miss the rate effect.
03The mechanism
Imbibition is a rate process. The seed must reach a critical hydration within a window before metabolism can restart, and slow delivery allows the seed to lose water back to the substrate.
That makes the rate the trigger, and predicts that substrates with high matric potential but low conductivity should fail despite being wet.
04What this is not
Those models predict from total water. This predicts from delivery rate, which explains failure on wet but slow substrates.
05Predictions
- P1Germination should track imbibition rate.
- P2Slow wet substrates should fail.
- P3Rate should predict better than content.
06Refutation
Germination tracking moisture content at controlled rate would restore the content model.
07What it changes
It would change sowing advice and substrate design.