FACTORS AFFECTING RATE OF TRANSPIRATION

light intensity

does not affect evaporation of water

in daylight increased photosynthesis keeps stomata open

to increase CO2

but this allows water vapour to diffuse out

speeding up transpiration

humidity

temperature

air movement

evaporation of water more rapid into warm air / increased temperature

this cools the leaf and does not kill the plant

less water evaporation when it's cold

dry air increases transpiration

increased air movement increases water vapour

increases rate of transpiration

leaf structure

structures that reduce transpiration rate

  • thick, waxy cuticle
  • sunken stomata
  • rolled up leaves, with stomata underneath
  • needle-shaped