Transcript Watch it Grow!!! Seeds and germination - Arcola High School

WATCH IT GROW!!!
SEEDS AND GERMINATION
Mahomet-Seymour High School
Would you Believe…

A corn plant is bigger than a Redwood Tree?

Wheat can live longer than an Oak Tree?
You Better Believe It…
CORN
Wheat
Redwood Tree
Oak Tree
Objectives…
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
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
Define what a seed is and describe its function.
Discuss the parts of a seed and describe their
functions.
Compare and contrast a monocotyledon and a
dicotyledon.
Understand the general requirements of
germination.
Discuss the steps in germination.
What is a seed?

Seeds can be thought
of as devices that
protect embryos until
they encounter
conditions that are
suitable for growth as
independent plants.
What are the parts of a seed?

Seed Coat: the outer protective layer of a seed.
 Protects
the seed from damage.
 Aids in Dormancy

Cotyledon: part of the embryo of the seed.
 Generally
becomes the first leaves of the plants to
emerge.


Endosperm: tissue within the seed that act as food
for the undeveloped embryo.
Embryo: contains all of the parts for the plant to
grow.
What are the parts of a seed?


Radicle: the part of the embryo that emerges to
produce a temporary root system.
Hypocotyl: the part of the embryo that breaks
through the soil and forms a small stem.
 Only


present in dicotyledons.
Epicotyl: the part of the embryo that emerges from
the soil to produce the first leaves.
Hilum: present on pod seeds, this is the attachment
point of the seed to the pod.
What are the parts of a seed?
Monocotyledon
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Seed Coat
Cotyledon (x1)
Endosperm
Embryo
Epicotyl
Radicle
Dicotyledon
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Seed Coat
Cotyledon (x2)
Endosperm
Embryo
Radicle
Hypocotyl
Epicotyl
Monocotyledon
Dicotyledon
4 General Requirements for
Germination…

Water: needed for imbibition.
 Causes

seed to swell and embryo to grow.
Oxygen: need for gas exchange.
 Available

Temperature: soil temperature needs to be at an
appropriate level for growth.
 Can

in soil pore
vary between plants
Light or Darkness: important for seeds that
germinate on top of the soil.
What is dormancy?

Dormancy: a period of
non-growth.
Seeds need to remain
dormant until the
conditions for growing
are right.
 Recently some seeds
were found viable after
10-15 thousand years.
 Most seeds have a
viable life of 3-15 years

What are the stages in germination?
1.
2.
3.
4.
5.
Monocotyledon
Seed swells (imbibition)
Radicle grows downward
Epicotyl grows upward
New leaves form and photosynthesis occurs
A new root system develops
What are the stages in germination?
1.
2.
3.
4.
5.
Dicotyledon
Seed swells (imbibition)
Radicle grows downward
Hypocotyl forms an arch (neck) and breaks
through the soil
Epicotyl receives light and photosynthesis begins
New leaves form and the cotyledons fall off