The document discusses the process of transpiration in plants, including defining transpiration, describing the different types of transpiration (cuticular, lenticular, and stomatal), and outlining some of the internal and external factors that affect the rate of transpiration such as temperature, humidity, and soil moisture availability. It also examines how much water plants can transpire and the advantages of transpiration for plants.

1. 1
By
Dr.Thirunahari Ugandhar
Asst Prof of Botany
Govt. Degree College
Mahabubabad-506101 (T.S.)

2. The objects are:
Definition of transpiration
Understanding the process of
transpiration
Learning types of transpiration
Advantages of transpiration to plant
2

3. Definition of fruit
• Transpiration or water cycle:
process of water movement
is the
through
a plant and its evaporation from aerial
but also
parts especially from leaves
from stems and flowers.
Transpiration
3

4. Types of transpiration
1. Cuticular Transpiration:the loss of water in the
form of water vapour through the cuticle is known
as cuticular transpiration.
Transpiration throughcuticle
4

5. 2. Lenticular transpiration: Loss of water in the form of
water vapour taking place through the lenticels present
in woody stem and fruits is called as lenticular
transpiration. It amounts 1-5 percent of the total water
loss by the plant.
Types of transpiration
5

6. 3. Stomatal transpiration: Stomata are minute pores
confined to epidermis of green shoot and leaves. Opening
and closing of stomata are controlled by guard cells.
Maximum loss (80-90 percent of the total water loss) of
water from the plant tissues takes place through the
stomatal openings.
Types of transpiration
Cross section of leaf
6

8. How much water do plants transpire?
During a growing season, a leaf will transpire many times
more water than its own weight. An acre of corn gives off about
3,000-4,000 gallons (11,400-15,100 liters) of water each day, and
a large oak tree can transpire 40,000 gallons (151,000 liters) per
year.
8

9. Evaporation and transpiration
Evapotranspiration: is the sum of
both evaporation and transpiration - the way
water moves from the liquid state to the gaseous
state.
Evaporation: occurs when water becomes vapor
from bodies of water
Transpiration: occurs when water leaves a plant
as vapor
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10. Internal factors affecting on transpiration
10
1. Number of leaves: More leaves (or spines, or other
photosynthesizing organs) means a bigger surface area and more
stomata for gaseous exchange. This will result in greater water
loss.
2. Number of stomata: more stomata will provide more pores for
transpiration.
3. Size of the leaf: A leaf with a bigger surface area will transpire
faster than a leaf with a smaller surface area.
4. Presence of plant cuticle: A waxy cuticle is relatively impermeable
to water and water vapour and reduces evaporation from the
plant surface except via the stomata.

11. External factors affecting transpiration
Temperature: Transpiration rates go up as the
temperature goes up, especially during the
growing season, related to open and closed the
stomata.
Relative humidity: As the relative humidity of
the air surrounding the plant rises the
transpiration rate falls. It is easier for water to
evaporate into dryer air than into more
saturated air.
11

12. External factors affecting transpiration
Wind and air movement: Increased movement of the
air around a plant will result in a higher transpiration
rate. This is somewhat related to the relative humidity
of the air.
Soil-moisture availability: When moisture is lacking,
plants can begin to senesce (premature ageing, which can
result in leaf loss) and transpire less water.
Type of plant: Plants transpire water at different rates.
Some plants which grow in arid regions, such as cacti and
succulents, conserve precious water by transpiring less
water than other plants.
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13. Antitranspirant
• Antitranspirants :are compounds applied to the leaves of plants to
reduce transpiration. They are used on Christmas trees, on cut
flowers, on newly transplanted shrubs, and in other applications to
preserve and protect plants from drying out too quickly. They have
also been used to protect leaves from salt burn and fungal diseases.
13

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Outline….
• Definition of stomata.
• Structure of stomata.
• Processes of opening and closing of
stomata.
• Mechanism of stomata.
• What are the factors affecting stomata
movement?

15. What is Stomata?
• Stomata are pore in a plants skin through
which water and gases are exchanged the
plant and the atmosphere.
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9
Structure of stomata
 Each stoma in surrounded by a pair of kidney
shaped guard cells. Each guard cell is a modified
epidermal cell showing a prominent nucleus,
cytoplasm and plastids.
• The wall of the guard cell is differentially
thickened. The inner wall of each guard cell facing
the stomata is concave and is thick rigid.
• ఒక జత మూత్తపిండాల ఆకారింలో గార్డ్ కణాల చుట్ట
ూ
ఉన్న త్రతి స్ట
ో
ూ ా. త్రతి గార్డ్ సెల్ ఒక ముఖ్య మైన్
కింత్రకిం,
• సైటోప్ల
ా జిం మరియు స్ట
ప్ల
ా ిూక ాు చూపస్తున్న ఒక చివరి
ార్డు ఎపడెరమ ల్ సెల్.
• గార్డ్ యొకక గోడ యొకక గోడ భిన్న ింగా మింరింగా
ఉింటింది. స్ట
ో
ూ ాా ఎదుర్క ింటన్న త్రతి గాస్ట
ర్డ్ యొకక
లోరలి గోడ చీలమిండ మరియు మింరప్లటి రృఢమైన్ది.

21. The guard cells are surrounded by a variable
number of epidermal cells called subsidiary cells.
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28. 2
8
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Opening and closing of stomata
• Opening and closing of stomata takes place due
to changes in turgor pressure of guard cells.
• During the day water from subsidiary
enters the guard cell making the guard
cell
cells
fully turgid and the stomata open.
• During night time, water from guard cells
enters the subsidiary cells and as a result the
guard cells become flaccid due to decrease in
turgor pressure and the stomata close.

32. 3
2
 Mechanism of stomata
Many theories have been proposed
regarding opening and closing of stomata.
Some important theories are givenbellow..
1.Theories of photosynthesis in guard cell.
2.Starch sugar inter conversion theory.
3.Theory of glycolate metabolism.
4.Active potassium transport ion concept.

34. Active k+ transport ion concept
The concept of k+ ion transport was given by
Fujino. It was supported and elaborated by Levitt
and Rashke in 1975. it was appears to be an
active mechanism which needsATP.
Explanation the mechanism as follows…
Opening of stomata during day time (in present
of light)
Closing of stomata in Absence of Light
(Darkness/ Night time).
Role of plant Hormones in Stomata Movements.
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Opening of stomata during day time
Opening of stomata depends upon following
conditions:
• Presence of light.
• Decrease in starch contents of guard cells.
• Increase concentration of malic acid in
guard cells.
• Influx of k+ ions in guard cells.
• Efflux of H+ ions from guard cells.

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Con..
• Intake of cl+ ions by guard cells.
• Low co2 concentration in an around
guard cells.
• High pH (more than 7) in guard cells.
• High T.P in guard cells due to
endosmosis.

41. Closing of stomata in Absence of Light
Closing of stomata depends on following
conditions:
• Absence of light.
• Decreased concentration of malic acid in
guard cells.
• Efflux of K+ ions from guard cells.
• Acidic medium of the cell sap in guard cells.
• Loss of Cl- ions from guard cells.
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42. 13
Con…
• Increase CO2 concentration in and
around the guard cells.
• Presence of plant growth inhibiting
hormone abscissic acid.

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Factors affecting stomatal movement
1. Light:
light greatly influences the opening and closing
of stomata. It is stimulates production of malic
acid due to conversion of starch to sugar.
Stomata so not open in U-V light and green light
but remain opened in the the blue and red
regions of the spectrum.
2. Temperature :
Stomata open with rise in temperature and close
at lower temperature as light and temperature are
directly are directly related. Higher temperature
also case stomatal closure.
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44. 3.Potassium chloride:
Accumulation of potassium chloride causes
opening of stomata
4.OrganicAcid:
The increase of organic acid content in the guard
cells causes stomata to open.
5.Carbondioxide concentration:
At low concentration of CO2, the stomata open.
with increase in the concentration of CO2 ,the
stomata begin to close and when CO2
of cells is higher than its
in the air, the stomata completely
concentration
concentration
close.
15

45. 16
6.water: water is responsible for causing changes
in the turgor off the guard cells. Guard cells
become flaccid on losing water and stomata
close. when the guard cells become fully turgid
on water and stomata open.
7.Abscisic: Abscisic acid accumulates in the
leaves when the plants experience water stress
or water deficit. It has been observed that ABA
stimulates closure of stomata under these
condition.

47. Conclusion
• We know that stomata is a pore in a plants skin and
usually it is limited on the lower sides of the leaves.
• In monocots seed the stomata are equally distributed
on all sides and in aquatic plants stomata are present
on the upper surface.
• మేము స్ట
ో
ూ మా మొకక ల చరమ ింలో ఒక
రింత్రిం మరియు సాధారణింగా ఆకులు
దిగువ భాగాలలో రరిమితిం అని ాకు
తెలుస్త.
• Monocots సీడ్ లో stomata సాన్ింగా అనిన
వైపులా రింపణీ మరియు నీటి మొకక లు లో
stomata ఉన్న త ఉరరితలింపై ఉన్నన యి
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48. 11/28/2013
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