transpiration rate is increased by four main things
light intensity
The brighter the light, the
greater the transpiration rate.
Stomata begin to
close as it gets darker.
Photosynthesis can't happen in
the dark, so they dont need to be
open to let co2 in. When
stomata are closed, water can't
escape
temperature
The warmer it is, the faster
transpiration happen. When it's
warm the water particles have
more energy to evaporate and
diffuse out of the stomata
air movement
If there's lots of air movement (wind) around a leaf,
transpiration happens faster. If the air around leaf is
very still, the water vapour just surrounds the leaf
and doesn't move away. This means there's a high
concentration of water particles outside the leaf as
well as inside it, so diffusion doesn't happen
quickly. If it's windy, the water vapour is swept away,
maintaining a low concentration of water in the air
outside the leaf. Diffusion then happens quickly,
from an area of high concentration to an area of low
concentration
air humidity
If the air around the leaf is very dry, transpiration
happens more quickly. This is like what happens with
air movement. If the air is humid there's a lot of water in
it already, so there's not much of a difference between
the inside and the outside of the leaf. Diffusion happens
fastest if there's a really high concentration in one
place, and a really low concentration in the other
Stomata open when the guard cells become turgid and closes when they become flaccid