Dormancy Flashcards
Define dormancy
Dormancy is a resting period when seeds undergo no growth and have reduced cell activity or metabolism
period of low metabolism in a seed when conditions for growth are unfavourable
List the four different ways dormancy can be brought on.
Growth inhibitors
Impermeable testa
Tough testa
Lack of suitable growth indicator
Explain how growth inhibitors bring on dormancy.
2
Growth inhibitors such as abscisic acid may be present in the outer part of the seed
These inhibitors delay growth until they are broken down by water, cold or decay
Give an example of a growth inhibitor.
Abscisic acid
Where may growth inhibitors be present in the plant?
In the outer part of the seed
When is dormancy caused by growth inhibitors stopped?
When the outer part of the seed is broken down by water, cold or decay
Explain how an impermeable testa brings about dormancy.
2
The testa (seed coat) may be impermeable to water or oxygen
Eventually the testa decays and breaks down, allowing water and oxygen to enter the seed
What is the testa?
The seed coat
What may the testa be impermeable to?
Water or oxygen
When is dormancy caused by an impermeable testa stopped?
2
When the testa eventually decays and breaks down
This allows water and oxygen to enter the seed
Explain how a tough testa brings about dormancy.
The testa may be too tough to allow the embryo to emerge
Explain how the lack of a suitable growth regulator brings about dormancy.
(2)
There may be a lack of a suitable growth regulator needed to stimulate growth
The regulator may be produced due to increased light or temperatures in spring
When is dormancy caused by the lack of a suitable growth regulator stopped?
When there is an increase in light or temperatures in spring
