investigating transpiration practical

• Factors that effect transpiration rate:

  • light intensity - stomata open during the day for photosynthesis
  • temperature - in warmer conditions the water on the surface of the leaf can evaporate faster
  • humidity - the drier the air the more the water potential gradient is increased, increasing the rate of transpiration
  • air movement - lots of wind blows water molecules away from the stomata, increasing transpiration
• a potometer can measure water uptake by the plant and can be used to estimate how different factors affect the transpiration rate
• the shoot must be cut underwater to prevent air entering the xylem