Factors affecting transpiration
Factors affecting transpiration
Factors Transpiration Humidity Decreases Increases
Temperature Increases Increases
Wind Increases Increases
Light Increases Increases
Higher conc. of water vapour (100% saturated)
The drier the air, the steeper the concentration gradient, the faster the rate of transpiration.
In plastics bag – 90% humidity
No plastics bag – 70% humidity
Factors affecting transpiration
Factors Transpiration Humidity Decreases Increases
Temperature Increases Increases
Wind Increases Increases
Light Increases Increases
Guard cells turgid
Stoma Opens
Guard cells flaccid
Stoma Closes
day time night time
Stoma
Think about it!!
Why placing the vegetables in a plastic bag helps to reduce
transpiration?
It helps to keep the humidity of the air surrounding the
vegetables high.
Wilting
What happens to the leaves when they wilt?
Rate of transpiration > rate of absorption of water
• How does wilting benefits the plants?– When leaves fold up, the surface area exposed to
the sunlight is reduced. – Stomata closes – Transpiration decreases
Wilting
• Disadvantages of wilting – Stomata closes– Carbon dioxide cannot diffuse into the leaves– Carbon dioxide becomes the limiting factor for
photosynthesis
Wilting
How to reduce transpiration?
Guard cells
Lower epidermis
Guard cells
Lower epidermis
Desert plant Normal condition
Habitat of marram grass
Leaves of marram grass
Guard cells
Hawaii Silversword
Leaves
Flowers
Guard cells
Lower epidermis
Guard cells
Leaves covered with silver hairs
Guard cells
Lower epidermis
Desert plant Adaptations:
•Sunken stomata
How it helps:
•The enclosed region around the stomata helps to retain water vapour
•increases humidity
Guard cells
Adaptations Functions Leaves curved up Reduce exposure to wind
and high temperature Hairs surround grooves Traps water vapour
Adaptations:
- Leaves covered with silvery white hair
How it helps:
-Reflect light lowers temperature of the leaves