Download Germination


Germination
Biology 104
Authors:
What conditions are required to make a
seed “germinate”?
•
Germination begins with imbibition, as the seed
absorbs water to make the seed coat permeable.
•
Imbibition breaks dormancy, which allows
germination to begin.
•
Seeds need moisture, proper temperature,
darkness and light.
What does germinate mean?
 Germinate- To begin to grow or develop, to develop
into a plant or individual as a seed spore or bulb. To
put forth shoots; sprout; pullulate.
Why do germinated seeds produce roots
first? Why not leaves first?
 The part of the plant that emerges from the seed
first is the embryonic or primary root. This allows
the seedling to become anchored in the ground,
and start absorbing water.
 After the roots absorb water, the embryonic shoot
emerges from the seed.
Where does the energy and material
come from to create the growing root?
 The seed has energy and raw material stored in the
cotyledons or the endosperm, which supports the
growth of the plant until it is able to
photosynthesize.
Why don’t all seeds germinate at the
same time? Why do some germinate
faster and others a little slower?
 Germination Time varies with temperature so expect
considerable variation.
 Growing days are a certain number of days when
growing conditions are favorable. If the plant does not
get enough growing days it will die before flowering.
What would be the consequences of germinating too
soon or too late? Would this make any difference if
these plants were growing “in the wild”? Why might
some not have germinated at all?
 If a seed germinates too early it might exhaust its
food reserves before it ever touches the ground,
environmental conditions that are suitable for
seedling growth might not coincide with seed
maturity. Example: if a seed germinates in late
summer then it will have to face the cold of
winter.
 Common causes of failure are soil: being too heavy,
wet or cold, or allowed to dry out, not given slow
seeds long enough to come up, pest eating the
seeds, not giving dormant seeds the proper pretreatment, poor air circulation, and over-watering.
Reasons of burning out are due to placing seeds in
full sun, or outdoor conditions too quickly.

Often, seeds require a preceding period of dormancy.

Dormant- inactive, latent, but capable of being activated, suspension of
metabolic process.

Seeds of many temperature-climate angiosperms will germinate only
after a prolonged period of cold. An inhibitor within the seed usually
abscisic acid, or ABA, is gradually broken down at a low temperature until
finally there is not enough to prevent germination when other conditions
become favorable.

This is an obvious mechanism of survival, preventing seeds from
germinating during an unseasonably warm spell in the autumn.

ABA- plant hormone that maintains a water balance of plants, prevents
seed embryos from germinating, induces the dormancy of seeds.
Sources:
 Dictionary.com
 Wikipedia
 Biology: Life on Earth
 Lovetoknowgardner.com