another offering to high school students.

1. SEED
STRUCTURE &
GERMINATION
DR.GURMINDER RAWAL

2. Fruit
➢ Contains seed
➢ Ovarian walls become fruit
walls
➢ Protects seed & nourishes it
➢ Helps in seed dispersal
➢ Mango, Coconut, Pea

3. Grain
➢ Fruit wall and seed coat
fused together
➢ Maize, Wheat, Barley,
Rice, grasses

4. SEED
➢ Ripened ovule after fertilization
➢ Contains embryo(dormant)
producing a new plant
➢ Embryo can with stand
extreme
conditions(temperature and
weather)
➢ Covered by seed coats
➢ Food stored in it as cotyledon
or endosperm
➢ Continuation of species

5. ➢ Continuation of species
➢ Used as food directly
➢ Oil extracted from them
➢ Used as medicines
➢ Malt extracted from seeds
➢ Mustard, Sunflower, Ajwain,
Fennel, Sesame

6. Monocotyledonous &Dicotyledonous Seed
➢ One cotyledon for storage of food in monocots
➢ Two cotyledons in dicots

7. Seed Size variation
➢ Very small(minute)-
Poppy, Orchids
➢ Large-Watermelon ,
Mango
➢ Largest-Coconut
weighing in kilos
➢ Outer surface of seeds
can be smooth, wavy,
spiny, hairy etc.

8. Albuminous and Exalbuminous Seeds
➢ Albuminous/endospermic seeds are
the seeds which have food stored in the special
nourishing tissue called as endosperm that remains
persistent till maturity e.g. Cereals, Grasses, Maize
➢ Exalbuminous seeds are the seeds which have the
stored food and the cotyledons in a special
structure called as kernel. It does not remain until
the embryo is mature e.g. Pea, Gram, Rajma

9. Albuminous and Exalbuminous Seeds

10. Structure of Bean Seed
(external)
➢ Seed Coat
1. Testa: The protective layer on the
outside is called a testa which
is usually very thin but tough. Within
the surface of the testa, there is a
tiny opening called the micropyle,
which is where water can enter and
start the germination process,
breaking the dormant stage.

11. (external structure contd.)
2. Tegmen: Testa encloses a thin ,
papery layer.
3. Hilum: The hilum, or scar, on a bean
is the site where the bean originally
attached to the fruit of the plant.

12. ➢ Cotyledons: The cotyledons are
the two large parts of the bean
seed that take up most of the
space within the bean.
➢ These serve as food storage for
the young bean plant until it
grows large enough to support
itself.
➢ Upon germination,
the cotyledon usually becomes
the embryonic first leaves of a
seedling.
Structure of Bean Seed (internal)

13. (internal structure contd.)
➢ Cotyledon: In some plants, this
contains high quantities of starch,
in other plants this role is
performed by an endosperm.
In monocotyledons, there is just
one cotyledon whereas
in dicotyledons there are two.

14. (internal structure contd.)
➢ Radicle: The embryonic root which
will develop into the primary root of
the plant. It is usually the first part of
the embryo to push its way out of the
seed during germination.
➢ Plumule: The embryonic shoot. It
appears as a bud which will give rise
to the shoot and the remaining
structures in the plant.

15. ➢ Embryo: The embryo is the infant
plant made up of two parts: the
radicle, or the first root, and the
plumule, or the first leaves. When
water enters the micropyle, the
radicle starts growing and moves
down and out through the
micropyle into the soil below and
the plumule starts growing upwards.
(internal structure contd.)

16. Structure of Corn Seed
➢ Monocot seeds are mostly endospermic
except orchids where seeds are non-
endospermic.
➢ In Cereals, maize seed coat is fused with
fruit coat and called Grain. Seed coat
called Pericarp.
➢ Endosperm: In many plants, a separate
part for storage of starch develops and
this is called the endosperm. It is seen in
maize and wheat. It is separated from
embryo by a proteinaceous aleurone
layer.

17. Structure of Corn Seed
➢ It contains one cotyledon called
scutellum and shoot axis.
➢ The lower part of the axis is the
radicle, covered by a sheath
called coleorhiza.
➢ The upper part of an axis is called
plumule, covered by a sheath
called coleoptile.
➢ Aleurone layer is a proteinaceous
layer that separates endosperm
from the outer covering.

18. Seed Dormancy
This is a condition in which the seeds are prevented
from germinating even under favourable conditions.
During seed dormancy:
1.The seed coat, which is resistant to water and gases,
restrict water uptake and oxygen exchange.
2.The seeds with undeveloped or immature embryo do
not germinate.
3.Certain seeds contain plant growth regulators which
inhibit seed germination.
4.Some seeds require more time for their germination.

19. Germination of Seeds
➢ Germination is the resumption of
growth of the embryo plant inside
the seed. Germination is affected by
both biotic as well as abiotic factors.
➢ Two types of germination
i. Epigeal germination
ii. Hypogeal germination

20. Abiotic factors
1) Water- For activation of enzymes and resumption of
biochemical activities
2) Light- Seeds must not go very deep in soil
3) Temperature- (25 -35 degree C)
4) Aeration(Oxygen)- Adequate amounts of oxygen to
meet the requirements of growing embryo
Biotic factors
1) Viability of seed
2) Dormancy of seed

21. Epigeal Germination
➢ Epigeal germination is a
botanical term indicating
that the germination of a
plant takes place above
the ground. An example of
a plant with epigeal
germination is the common
bean.

22. Hypogeal Germination
➢ Hypogeal germination implies that the
cotyledons stay below the ground. The
epicotyl (part of the stem above the
cotyledon) grows, while the hypocotyl
(part of the stem below the cotyledon)
remains the same in length. ... Plants
that show hypogeal germination grow
relatively slowly, especially in the first
phase.

23. Viviparous Germination
➢Viviparous plants
produce seeds that germinate
before they get detach from
the parent plant.
➢ This phenomenon is commonly
observed in mangroves(for
example - Rhizophora species).
➢ The seedling germinates and
grows under its own energy
while still attached to its parent.

24. Viviparous Germination in Mangrove Plants

25. & HAPPY LEARNING