Plant Water Use Effectiveness
Invited Plenary
Professor Graham Farquhar
Distinguished Professor
The Australian National University
Canberra
Biography
Professor Farquhar studied physics and mathematics at Monash University and the Australian National University, did an honours year in biophysics at the University of Queensland, and then completed his PhD in environmental biology at the ANU in 1973. He was next a postdoctoral fellow at the Plant Research Laboratory of Michigan State University and then returned to the ANU where he studied photosynthesis and plant water use. For this work he was elected Fellow of the Australian Academy of Science in 1988. His work on stable isotopes and water-use efficiency led to a CSIRO Medal for research achievement in 1991. Ten years later after two wheat varieties were released with improved performance in dry environments he shared the CSIRO Medal for team research. He extended his interests to global change and was elected to Fellowship of the Royal Society (of London) in 1995. In 2001 he was the leading Australian Citation laureate. In 2008 he shared the Nobel Prize awarded to the Inter-governmental Panel on Climate Change. He is currently Secretary Biological and Vice-President of the Australian Academy of Science.
Synopsis – ‘Plant Water-Use Effectiveness’
Water is the single greatest limitation to crop production world-wide. The stable isotopes of carbon in leaves can be used to compare different genotypes for the ratio of carbon gain (photosynthesis) to water loss (transpiration). This comes about because the isotope effect of diffusion of carbon dioxide into a leaf is much less than that for conversion of that CO2 into carboxylation products by the enzyme Rubisco. A particular species may have a high water-use efficiency because of high photosynthetic capacity or because of low stomatal conductance. The isotopes of oxygen can be used to compare stomatal conductance across genotypes. The two results are complementary. Recently it has been argued that water-use efficiency may be the wrong direction for breeders to go, except in the case of very dry environments, and that water-use effectiveness may demand the greatest possible transpiration. The two ideas will be reconciled in the talk.