Sweating
in the sun: Trading water for carbon
Presented by Dr
John Evans
Environmental
Biology Group
Photosynthesis
by leaves has a remarkable influence on Earth's atmosphere
but photosynthesis is also being affected by the rising
CO 2 concentration. While CO 2 is being taken up from
the atmosphere, water evaporates in a process called
transpiration. Transpiration accounts for about three
quarters of all water that evaporates from the global
land surface. The exchange of H 2 O, CO 2 and O 2
molecules between the leaf and the atmosphere occurs
through stomatal pores in the leaf surface. Stomata
respond to many environmental signals, such as light,
CO 2 and humidity. While empirical relationships exist
for predicting how stomata respond, mechanistic understanding
remains elusive. In Australia , as in many places
around the world, water is the currency plant use
to buy carbon, so improving our understanding of stomata
offers the promise of improving crop yields.
This session
will present the basic principles of leaf gas exchange
and mathematical modelling of photosynthesis. You will
get hands on experience with the best modern field portable
instrument and measure short term responses to atmospheric
CO 2 concentration and light intensity .
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