Factors affecting transpiration

1. Factors affecting transpiration

2. Factors affecting transpiration

3. Higher conc. of water vapour (100% saturated) In plastics bag – 90% humidity No plastics bag – 70% humidity The drier the air, the steeper the concentration gradient, the faster the rate of transpiration.

4. Factors affecting transpiration

5. night time day time Guard cells turgid Stoma Opens Guard cells flaccid Stoma Closes Stoma

6. 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.

7. Wilting Rate of transpiration > rate of absorption of water What happens to the leaves when they wilt?

8. Wilting • How does wilting benefits the plants? • When leaves fold up, the surface area exposed to the sunlight is reduced. • Stomata closes • Transpiration decreases

9. Wilting • Disadvantages of wilting • Stomata closes • Carbon dioxide cannot diffuse into the leaves • Carbon dioxide becomes the limiting factor for photosynthesis

10. How to reduce transpiration?

11. Normal condition Desert plant Guard cells Guard cells Lower epidermis Lower epidermis

12. Guard cells Habitat of marram grass Leaves of marram grass

13. Hawaii Silversword Flowers Leaves

14. Guard cells Guard cells Lower epidermis Leaves covered with silver hairs

15. Desert plant • Adaptations: • Sunken stomata • How it helps: • The enclosed region around the stomata helps to retain water vapour • increases humidity Guard cells Lower epidermis

16. Guard cells

17. Adaptations:- Leaves covered with silvery white hair How it helps: -Reflect light lowers temperature of the leaves