This presentation describes about the dormancy, types of dormancy (seed dormancy and bud dormancy) as well as methods to overcome the bud and seed dormancy in detail.

3.  Dormancy
 Seed Dormancy
 Reasons for Seed Dormancy
 Methods of Breaking Seed Dormancy
 Advantages of Seed Dormancy
 Disadvantages of Seed Dormancy
 Bud Dormancy
 Reasons for Bud Dormancy
 Methods of Breaking Bud Dormancy
 Seed and Bud Dormancy

5.  A period in which a plant does not grow,
awaiting necessary environmental conditions such
as temperature, moisture, nutrient availability, etc.
 In plant physiology, dormancy is a period of
arrested plant growth.
 A state when organisms are in
unfavourable conditions, and slow down
their metabolic processes to a minimum to
retain resources until conditions are more favourable.
 Plants may do this when their is a lack of water,
while animals, such as the garden dormouse, hibernate,
which is also a form of dormancy.

8. Many seeds are unable to
germinate even under ideal
conditions of oxygen,
water and temperature. It
is due to internal
conditions. The resting
stage of seed before
germination is termed as
seed dormancy.

9.  Seed dormancy can be defined as the state or a
condition in which seeds are prevented from
germinating.
 Even under the favourable environmental
conditions for germination including, temperature,
water, light, gas, seed coats, and other mechanical
restrictions.
 The main reason behind these conditions is that they
require a period of rest before being capable of
germination.
 These conditions may vary from days to months and
even years.
 These conditions are the combination of light, water,
heat, gases, seed coats and hormone structures.

10. Some seeds are shed before
the maturation of embryo.
Such seeds are not fit to
grow. They require a period
during which certain
changes occur within the
seed, such as enzymatic
activity and respiratory
activation,. Germination
occurs only when the
embryo development is
complete. Dormancy due to
immature embryo is
common in Orchidaceae,
Ranunculus, Fraxinus etc
In some seeds chemical
acts as inhibitors for
germination. In tomato
fruits, ferulic acid is an
inhibitory substance.
Certain inhibitory
substances are phenolic
acids, abscisic acid,
coumarine and para-
ascorbic acid, they are
found in different kinds of
fruits.
It is the most common
factor for seed dormancy.
It prevents the absorption
of water and gaseous
exchange. In addition o
hard seed coat, seeds of
many members of
Leguminaceae have
external waxy coating.
Hard seed coat Immature embryo Chemical inhibitors

11. Chemical inhibitorsImmature embryo
Hard seed coat

13. The natural breaking of Seed Dormancy
Nature of dormancy stops when the embryo gets appropriate environment such as
adaptive moisture and temperature. The seed coat that exists in many species
becomes permeable due to the rupturing of smoothing action of natural agents like
microorganism, temperature, and abrasion by the digestive tract of birds and
animals that feed on these seeds. Other natural methods include:
o Completion of the over-ripening period.
o Leaching of inhibitors present in the seed coat.
o Inactivation of inhibitors by the supply of cold, heat, and light.
o Leaching of the excess and highly concentrated solutes from the seeds.
o Production of growth hormones which can neutralize the effect of inhibitors.
Artificial Overcoming of Seed Dormancy
Some of the artificial methods used for breaking seed dormancy are listed below:
Action with hot water for termination of waxes, surface inhibitors, etc.
o Rupturing of seed coats by filing, chipping, or threshing through machines.
o Exposure to heat, cold or light, depending upon the type of seed dormancy.
o By applying Hydraulic pressure for 5 to 20 minutes in order to weaken the
tough seed coats.
o Seed coats are treated with concentrated sulphuric acid for removing all traces
of the mineral acid.

15. Scarification involves weakening, opening, or
otherwise altering the coat of a seed to encourage
germination.

16.  When the dormancy is due to hard coat, it is
impermeable to water and oxygen.
 The scarification method is used to break the
dormancy of seed.
 In this method, the seed coat becomes permeable
to water and oxygen.
 By cutting or breaking the seed coat or by
chemical treatment.
 In this way, scarification is either mechanical or
chemical.

17.  It is a technique for overcoming the effect of an
impermeable seed-coat.
 It can be done by rubbing seeds between two
pieces of sandpaper, or using a file, a pin, or a
knife to rupture the seed coat.
 Seed may also mixed with the coarse sand and
shaken vigorously in a jar.
 Even a vise can be used to squeeze seeds along the
suture until they crack open.
 After the seeds have been cut of rubbed soak them
in cold water for 24 hours before sowing.

18. aMechanical Scarification

19.  It involves the use of one or more chemicals to
promote the germination.
 It can involve imbibing or soaking seeds in precisely
concentrated acidic or basic solutions for varying
amounts of time.
 Wear goggles and protective clothing at all times.
 Acid treatments are often used to break down
especially thick impermeable seed coats.
 In this method, seeds are dipped into strong acid or into
organic solvents such as acetone or alcohol.
 Seeds are placed in concentrated H2SO4 will become
charcoal in time.

20.  The temperature of the acid and the length of the
time in which seeds are soaked are very important.
 The acid should be used at room temperature for a
period of few minutes to several hours depending
on the seed type.
 The seeds should be immersed in acid in a glass or
china dish.
 It should be stirred occasionally with a glass rod.
 The seeds should be removed from the acid just
before any acid penetrates the seed coats.
 Then washed it under cold water for 10-15 minutes
to remove any remaining acid.

21. Chemical Scarification

22. THERMAL SCARIFICATION
Thermal scarification can be achieved by briefly
exposing seeds to hot water, which is also known as
hot water treatment. In some chaparral plant
communities, some species' seeds require fire and/or
smoke to achieve germination.

23.  This is by far the most common and one of the easiest
ways of scarification.
 Place a teaspoon of seed in a cup then fill the cup with
boiling water, leave to cool.
 Let the seed soak in the water for twenty four hours
and then sow.
 You can usually tell the seed that has been impregnated
with water as it will have started to swell.
 Any seed that is not showing sign of impregnation can
be left soaking for a couple of days and if it still hasn’t
started to swell then it can be retreated with boiling
water.
 The container used for this treatment should not be
made of aluminum as it may be toxic for the seeds.

24. HOT WATER TREATMENT

25. Seeds Sowing

26.  Oven or dry heat is not often
recommended and the
temperature required are
more suitable to an
incubator than a kitchen
oven.
 In this method, seeds should
be placed in shallow
containers in a preheated
incubators or oven.
 The specific temperature
and duration depend on the
species.
 The temperature suggested
is between 1800-2120F.
 Seeds of some genera have
tough, thick seed coats and
germinate best when subjected
to the heat of fire.
 Seeds should be sown in the
fall in a slightly moist medium
but not watered.
 A layer of dry pine needles,
four to six inches deep, should
be placed over the top of the
seedbed.
 A few small pieces of wadded
paper will help to ignite the
material.
 One or two strips of aluminum
foil placed over the exposed
edges of wood container will
prevent it from burning.

28.  Stratification is a treatment given to seeds of some plants species
that requires a period of cold temperatures (40C-80C) in order to
germinate.
 For example, some seeds of species like peach, apple, plum,
cherry etc.
 They only germinate when they are exposed to well aerated
moist conditions under low temperatures for weeks or months.
 It is believed that embryos of those seeds which require
stratification are immature in the sense.
 It requires some chemical changes must take place to initiate
seed germination.
 Natural stratification occurs when seeds are shed, they are
covered with soil, debris and snow.
 In artificial stratification, the layers of seeds are kept in sand or
any other material.

29.  Some seeds contain germination inhibitors that break down when exposed to
cold temperatures.
 This is nature’s way of preventing the seed from germinating before spring
arrives.
 Soaking the seeds in cold water for 6–12 hours immediately before placing them
in cold stratification.
 Stratification exposes the seeds to cold temperatures in the refrigerator,
simulating a short winter.
 When brought back to room temperature, they germinate readily.
 Large seeds are easy to stratify by placing them between moist paper towels or in
a jar of moist sand in the refrigerator.
 It’s best to plant small seeds in a tray of soil before refrigerating them.
 It takes between two and six weeks of cold temperatures to break down the
inhibitors, depending on the type of seed. Seeds require moisture, cold and
oxygen.
 In general, this period of time allows an undeveloped embryo to mature.
 This cold moist period triggers the seed's embryo; its growth and subsequent
expansion eventually break through the softened seed coat in its search for sun
and nutrients.

30. COLD STRATIFICATION

31. REFRIGERATOR

32.  Warm stratification means to place seeds in contact
with warm, moist soil (usually to simulate the end
of summer and usually followed by cold
stratification).
 Warm stratification requires temperatures of 15-
20°C (59-68°F).
 In many instances, warm stratification followed by
cold stratification requirements can also be met by
planting the seeds in summer in a mulched bed for
expected germination the following spring.
 Some seeds may not germinate until the second
spring..

34. Seeds may be kept
outdoors through the
winter in lined pits or
raised beds. They must
be protected from
freezing, drying and
rodent predation (use
wire netting in the
soil). Pits or beds are
layered with clean sand,
medium with seeds,
more clean sand, etc.
Outdoor Planting is
that some categories of
seeds may simply be
planted outdoors in the
fall and natural
stratification is allowed
to happen.
Outdoor Stratification Outdoor Planting

35.  Impaction means to strike
something with force.
 This method implies to
the vigorous shaking of
the seeds.
 This method is used when
the micropyle is blocked
by a cork-like substance,
strophiolar plug, which
prevents the penetration
of oxygen and water.

36.  Three chemical that have proven very helpful in breaking
certain types of dormancy.
 Gibberellic acid (GA3) conc. Of 100 ppm, Potassium
nitrate (0.2 %) and Thiourea (0.5 to 3%).
 The aqueous solution of these chemicals should be used at
room temperature.
 The concentration and the length of the treatment depends
on the species to be treated.
 Seeds soaked in GA3, or thiourea should be stirred
occasionally and not rinsed afterwards, unless specified,
but sown immediately.
 After this soaking they can also be air-dried and stored for
short periods and then sown or given a subsequent
treatment.
 The no-rinse afterwards also applies to the use and
potassium nitrate and hydrogen peroxide, other chemicals
occasionally as aids to germination.

37.  Induction and release of seed dormancy is mainly
under the control of abscisic acid (ABA)
and gibberellic acid (GA).
 ABA promotes seed dormancy and germination
inhibition. Action of ABA is counteracted by GA,
which promotes seed germination at appropriate time.
 Gibberellins (GAs) break seed dormancy and
promote germination (1, 2), and several
other hormones, including brassinosteroids, ethylene,
and cytokinin, have also been shown to promote seed
germination (3, 4).
 However, abscisic acid (ABA) is the
only hormone known to induce and maintain seed
dormancy.

38. The mulch treatment
hastens the microbial
breakdown or softening
of the seed coats.
For the occasional
species whose seed coats
contain readily water-
soluble, germination-
inhibiting chemical, this
substance can be
removed by soaking the
seeds in tap water or by
leaching the seeds in
slowly tap water for
various lengths of time
just prior to soaking.

40.  Dormancy allows the seeds to remain in suspended
animation without any harm during drought, cold or
high summer temperature.
 Dormancy help seeds to remain alive in the soil for
several years provide a continuous source of new
plants even when all the mature plants of the area have
died down due to natural disasters.
 It ensures the seeds only germinates under the
favourable conditions.
 In temperate zones, the dormancy of seeds helps the
plants to tide over severe cold which may be injurious
for their vegetative and reproductive growth.
 In tropical regions, the dormancy of seeds resulting
from their impermeable seed coats ensures good
chances of survival during water stress.

41.  It also enables the proper dissemination (dispersal)
seeds to distant places from the unfavourable
environment.
 It also ensures the agricultural seeds to be stored
artificially. Dormancy of seeds in many cereals is of
utmost important to mankind.
 If these seeds would germinate immediately after
harvest in the field, they will become useless to man
for consumption as food.
 Rain, at that time of harvest or maturity, may spoil
entire produce by initiating germination. Thus it
enables storage of seeds for later use by animals and
man.

42.  No uniform germination.
 It is difficult to maintain plant population.
 It interferes in seed testing procedures.
 Seed remain naked during dormant period they get
shabby look.

44. A dormancy process in which
dormancy is induced,
maintained or broken in a bud.
Bud dormancy is a suspension of
most physiological activity and
growth that can be reactivated. It
may be a response to
environmental conditions such
as seasonality or extreme heat,
drought, or cold. The exit from
bud dormancy is marked by the
resumed growth of the bud.

45.  Bud is a undeveloped or embryonic shoot
and normally occurs in the axil of leaf or
at the tip of stem.
 Once form a bud may remain for
sometime in condition, or it may form a
shoot immediately.
 Buds may be specialized to developed
flowers or a short shoot, or may have
potential for general shoot development.
 The buds of many woody plants,
especially in temperate or cold climates,
are protected by a covering of modified
leaves called scales.
 Which tightly enclose the more delicate
parts of the bud.
 Many bud scales are covered by a gummy
substance which serves as added
protection.

46.  Perennial plants like shrubs, trees have to go through different
seasons in a year.
 The onset of winter is always an unfavourable season for the growth
and even survival of plants become difficult.
 Environmental signals such as temperature and light play crucial
roles in regulating development and release of bud dormancy.
Physiological signals including phytochrome, phytohormones, and
sugar are associated with changes in dormancy status that occur
when plants perceive environmental signals.
 Those of major importance in contributing to the onset of bud
dormancy include changes in temperature and photoperiod and the
availability of food, water, oxygen, and carbon dioxide.
 The winter season is an unfavorable season for the growth and
survival of the plants. In order to overcome the cold conditions the
buds undergoes a period of suspended growth also known as the bud
dormancy.
 This season stimulates the synthesis of growth inhibiting compounds
abscissin which dominates. ABA which induces the dormancy on
meristematic tissues of the plant body.

47. Reasons for Bud Dormancy

49.  Chilling method to break bud dormancy.
 Photoperiod to break bud dormancy.
 By using growth promoting hormones to break
bud dormancy such as gibberellins, cytokinin
and ethylene.
 By providing alternate temperature such as
high or low temperature also break the bud
dormancy.

50.  Chilling treatment can break the bud dormancy.
 By providing very low temperature to the plant, so their
enzymatic activity created.
 The chilling requirement (exposure
to temperature between 5 and 10°C) for
breaking dormancy of flower buds differs among species
and cultivars.
 The cold exposure of plants also releases them from
dormancy and buds start sprouting.
 The natural exposure to low temperature is during the
winter or during seasonal cool spells.
 The stimuli developed in response to low temperature are
accumulated in the buds which normally is expressed as
an effect on the quantitative increase in the growth of
buds in response to the increasing chilling duration.

51.  The photoperiodic effect either in breaking the
dormancy or induction of dormancy is explained on the
basis of phytochrome involvement.
 When long day conditions prevail, more amount of PfR
form of phytochrome accumulates in the cells.
 It initiates not only the synthesis of more GA and but
also it facilitates the release of it from the plastids into
the cytoplasm.
 Once GA is released, it brings about the activation of
dormant cells, and thus GA breaks bud dormancy.
 It is really very fascinating to understand the three way
interaction between phytochrome, photoperiod and
GA/ABA synthesis in imposing bud dormancy or
breaking it.

52.  Temperature regulates bud dormancy and
environmental stimuli perceived by the plant and
their correlation of environmental signals with the
built up of plant hormones and nucleic acids levels
lead to the further control of bud dormancy.
 Bud dormancy can also be induced by exposing
the plant firstly with low temperature and then
with high temperature.
 So this alternating temperature treatment break the
bud dormancy.

53.  The dormant buds can be induced to sprout again by treating with cytokinins and
gibberellins. But in natural course, the onset of spring and long photoperiods, the
dormant buds become active and develop into branches.
 Cytokinins are known to be synthesized in root tips but under cold conditions
because of the snow fall, the root meristems are very inactive and they don’t
synthesize sufficient quantities of cytokinin required for the buds to be active.
 That is probably one of the reasons why buds remain dormant. As soon as
cytokinins are provided to dormant buds, mitotic activity is initiated and buds start
sprouting. Besides, cytokinins also counteract ABAs inhibitory effect of the
metabolic activity level and promote growth activity.
 Another class of phytohormones, which overcomes the bud dormancy, is
Gibberellins. Now it is certain that Gibberellin synthesis takes place in
plastids. Moreover, the synthesis of GA and ABA starts from the same precursor
called mevolonate. Under short day conditions, the pathway from mevolonate is
directed towards ABA synthesis and GA synthesis is inhibited, but during long day
photoperiods it is directed towards GA synthesis and ABA synthesis is blocked.
 That is the reason why gibberellins under long day conditions or not light
treatment, break bud dormancy and nullify the effect of ABA present in such
dormant buds.

54. Methods of Breaking Bud Dormancy

55. Seed Dormancy Bud Dormancy
Seed dormancy is the phenomena
where the seed does not germinate
for specific period of time.
Seed dormancy is also the
phenomena where the bud does not
grow for specific period of time.
Gibberellins, cytokinin and ethylene
break seed dormancy.
Gibberellins, cytokinin and ethylene
break seed dormancy.
Abscissic acid promotes seed
dormancy.
Abscissic acid promotes seed
dormancy.

56.  Dr. Muhammad Fareed Akhtar, Botany For Degree Classes
Paper C&D
 https://en.wikipedia.org/wiki/Dormancy
 https://www.britannica.com/science/dormancy
 https://www.biologydiscussion.com/seed/seed-
dormancy/seed-dormancy-meaning-types-and-effects-
biology/34493
 https://en.wikipedia.org/wiki/Seed_dormancy
 https://homeguides.sfgate.com/methods-break-seed-
dormancy-73304.html
 https://biologyboom.com/methods-of-breaking-seed-
dormancy/
 https://thefactfactor.com/facts/pure_science/biology/seed-
dormancy/2123/

57.  https://www.slideshare.net/gohilsanjay3/bud-dormancy
 https://www.sciencedirect.com/topics/biochemistry-genetics-
and-molecular-biology/bud-dormancy
 https://www.frontiersin.org/articles/10.3389/fpls.2018.00657/f
ull
 https://plantcellbiology.masters.grkraj.org/html/Plant_Growth
_And_Development12-
Physiology_Of_Dormancy.htm#:~:text=Breaking%20Bud%2
0Dormancy%3A,active%20and%20develop%20into%20bran
ches.
 https://www.biologydiscussion.com/plant-physiology-2/bud-
dormancy/mechanism-involved-in-releasing-bud-dormancy-
plant-physiology/40323