Transpiration is the process by which a loss of water takes place in the form of water droplets from the aerial parts of the plant i.e, leaves ,lanticels , cutical, or bark of the plant.

1. BACHELORS OF SCIENCE 3rd YEAR
SUBJECT: BOTANY
TOPIC :-TRANSPIRATION,STRUCTURE &
PHYSIOLOGY OF STOMATA,MECHANISM OF
TRANSPIRATION,FACTORS OF TRANSPIRATION
WELCOME
TO
ALL OF YOU
FOR
TODAY’S PRESENTATION

2. TRANSPIRATION
• LOSS OF WATER IN THE FORM OF WATER VAPOURS FROM THE
AERIAL PARTS OF THE PLANT
• ROOTS ABSORB WATER FROM SOIL BY ACTIVE MOVEMENT OR
PASSIVE MOVEMENT
• THEN WATER MOVE IN THE XYLEM AND FORWARDS IN UPWARD
DIRECTION TO AERIAL PARTS
• THIS WATER THEN REACH IN LEAVES OF PLANT.
• THEN WATER TRANSPIRE IN THE FORM OF WATER VAPOURS
THROUGH STOMATA

3. TRANSPIRATION PATHWAY
V.T.S. OF A TYPICAL DICOT LEAF SHOWING THE MOVEMENT OF
WATER DURING TRANSPIRATION

4. TYPES OF TRANSPIRATION
TRANSPIRATION
STOMATAL
TRANSPIRATION
CUTICULAR
TRANSPIRATION
LENTICULAR
TRANSPIRATION
BARK
TRANSPIRATION

5. STOMATA
• STOMATA ARE SMALL PORES PRESENT IN THE EPIDERMIS OF THE
LEAF
• THESE REMAIN CLOSE AT NIGHT AND OPEN AT DAY TIME
• STOMATA REMAINS COVERED BY TWO GUARD CELLS & SUBSIDARY
CELLS
• IN MONOCOTS STOMATA IS PRESENT IN UPPER & LOWER
EPIDERMIS BUT DICOTS HAVE ONLY AT LOWER EPIDERMIS
• DICOTS HAVE KIDNEY SHAPED GUARD CELLS & MONOCOTS HAVE
DUMBLE SHAPED GUARD CELLS

6. STOMATA
OPEN AND CLOSED STOMATA

7. MECHANISM OF STOMATAL TRANSPIRATION
• THE OUTER WALL OF THE GUARD CELL IS THIN & ELASTIC AND
INNER WALL IS THICK
• GUARD CELLS ABSORBS WATER FROM NEIGHBOURING CELLS AND
INTERCELLULAR SPACES
• THEN THE GUARD CELLS BECOME TURGID DUE TO RUSHING OF
WATER FROM OUTSIDE TO INNER SIDE OF THE CELL
• OUTER WALL OF THE GUARD CELL BULDGE OUTWARDS & INNER
WALL BECOME CONCAVE,THIS RESULTS THE OPENING OF
STOMATA AND WATER COMES OUT / LOSS
• WHEN WATER LOSS, CELL LOOSE TURGIDITY,THICK WALL REVERTS
TO ITS ORIGINAL POSITION, NARROWING THE STOMATA & RESULTS
STOMATA CLOSE

8. PHYSIOLOGY OF SOMATA
WATER FROM
XYLEM
MESOPHYLL
CELLS OF LEAF
(M.C.) BECOME
TURGID
(O.P + D.P.D)
DECREASE IN
(M.C)
H2O RELEASE
INTO THE
INTERCELLULAR
SPACES
A. (O.P + D.P.D) OF
M.C INCREASES &
DRAW H2O FROM
XYLEM
B. INTERCELLULAR
SPACES ARE
CONNECTED TO THE
ATMOSPHERE
THROUGH STOMATA
AIR IS DRY & HAS
LOW WATER
POTENTIALTHAN
MOIST AIR
WATER VAPOUR
DIFUSSES OUT
THROUGH THE
STOMATA
WATER LOSS FROM
LEAVES,,M.C,XYLEM,S
TEM,ROOT,SOIL
PROCESS
CONTINUES

9. GUTTATION
• LOSS OF WATER IN THE FORM OF DROPS ALONG THE MARGINS OF
LEAF OR TIPS OF THE LEAVES IS KNOWN AS GUTTATION
• IT IS GENERALLY TAKES PLACE UNDER THE CONDITIONS OF HIGH
ROOT PRESSURE AND LOW TRANSPIRATION THROUGH
SPECIALIZED PORES CALLED HYDATHODES
• IT TAKE PLACE IN HERBACEOUS PLANTS e.g, GRASSES
• IT OCCURS DURING LATE NIGHT TIME

10. ADVENTAGES & DISADVENTAGES OF TRANSPIRATION
ADVENTAGES
1. ABSORPTION OF WATER.
2. TRANSLOCATION OF WATER & SALTS.
3. MINERALS ABSORPTION.
4. COOLING EFFECT.
5. MAINTANANCE OF INNER WATER BALANCE.
6. GROWTH AND DEVELOPMENT.

11. ADVENTAGES & DISADVENTAGES OF TRANSPIRATION
DISADVENTAGES
1. CREATION OF WATER DEFICT.
2. DECREASED CELL TURGIDITY.
3. CAUSE MID-DAY LEAF WATER DIFICT.
4. REDUCED GROWTH AND YEILD DUE TO HIGH TRANSPIRATION RATE
5. STUNTED GROWTH
6. LOSS OF WATER & IRRIGATION

12. FACTORS AFFECTING RATE OF TRANSPIRATION
A. INTERNAL FACTORS
1. LEAF AREA
2. LEAF STRUCTURE (PRESENCE OF THICK
CUTICLE,WAX,RESIN,SUBERIN COATING & COMPACT M.C.& SUNKEN
STOMATA)
3. AGE OF THE PLANT
B. EXTERNAL FACTORS
1. ATMOSPHERIC HUMIDITY
2. TEMPRATURE
3. LIGHT (OPENING THE STOMATA & INCREASE TEMPRATURE)
4. WIND VELOCITY
5. AVILABLE SOIL WATER

13. CREATED & PRESENTED BY
ATIF ALI ZAKIR
STUDENT OF MSC BOTANY II YEAR
SAIFIA SCIENCE COLLEGE BHOPAL
THANK YOU SO MUCH
FOR
ATTENDING THIS LECTURE