Dr. Farquhar has developed process-based models of photosynthesis, enabling the prediction of the environmental responses of carbon dioxide exchange between vegetation and the atmosphere, as well as models for the fractionation of the stable isotopes of carbon and oxygen during photosynthesis and transpiration. Doing so, he has made major contributions to the advancement of environmental and climate change sciences.
Photosynthesis by plants provides the foundational support to all ecosystems on Earth. Hence, functional understanding of photosynthesis is critically important for analyses of the environmental responses of agricultural production and ecosystem processes. Terrestrial plants control stomata in order to optimize the uptake of carbon dioxide (CO2) from the atmosphere while preventing excessive water loss via transpiration. Thus, the assimilation rate of CO2 cannot be considered separately from transpiration.
Dr. Graham Farquhar and colleagues developed a series of process models of photosynthesis based on the fact that the carbon assimilation catalyzed by Rubisco is a major rate-limiting step in photosynthesis (1?3). The original model, published in 1980, enabled quantitative analyses of CO2 exchanges between plants and the atmosphere in relation to multiple environmental factors. As such, it has been applied to a variety of research, ranging from cells and leaves to forest-stand levels (4). The model has been used in quantitative evaluations of how diverse plants in agricultural fields, grasslands, and forests respond to increases of atmospheric CO2 due to human activities, and how these responses are affected by water availability and temperature. Most importantly, it is incorporated in almost all of the existing models of the terrestrial biosphere carbon cycles, and as such, it is indispensable for climate change science.
Dr. Farquhar also developed process-based models for fractionation of stable isotopes of carbon and oxygen during photosynthesis and transpiration by terrestrial plants (5?7). These models have been used extensively in botany, agricultural science, environmental science, paleontology (tree ring analysis), and ecosystem ecology (isotopic analysis of the food chain). Dr. Farquhar continues to be actively engaged in pioneering research in botany and environmental science. As for his contribution to agricultural sciences, Dr. Farquhar assisted selections of drought-resistant varieties of wheat and peanut by utilizing his process-based models of photosynthesis (8), which led to the identification of key genes for efficient water use (9).
Dr. Farquhar has actively contributed to climate change science and development of science-based policies, for example as a member of the Intergovernmental Panel on Climate Change, and also as a scientific advisor and an Australian representative to the Kyoto Protocol negotiations.
In summary, for almost 40 years, Dr. Farquhar has contributed to the advancement of environmental science and climate change science. As climate change science becomes increasingly important, his process-based models of photosynthesis will continue to play a significant role at the global research fronts.
(1)Farquhar GD, et al. (1980) A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species. Planta 149: 78-90.
(2)von Caemmerer S & Farquhar GD (1981) Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves. Planta 153: 376-387.
(3)Farquhar GD & Sharkey TD (1982) Stomatal conductance and photosynthesis. Annu. Rev. Plant Physiol. Plant Mol. Biol. 33: 317-345.
(4)dePury DGG & Farquhar GD (1997) Simple scaling of photosynthesis from leaves to canopies without the errors of big-leaf models. Plant Cell Env. 20: 537-557.
(5)Farquhar GD, et al. (1982) On the relationship between carbon isotope discrimination and the intercellular carbondioxide concentration in leaves. Aust. J. Plant Physiol. 9: 121-137.
(6)Farquhar GD, et al. (1989) Carbon isotope discrimination and photosynthesis. Annu. Rev. Plant Physiol. Plant Mol. Biol. 40: 503-537.
(7)Farquhar GD, et al. (1993) Vegetation effects on the isotope composition of oxygen in atmospheric CO2. Nature 363: 439-443.
(8)Farquhar GD & Richards RA (1984) Isotopic composition of plant carbon correlates with water-use efficiency of wheat genotypes. Aust. J. Plant Physiol. 11: 539-552.
(9)Masle J, Gilmore SR & Farquhar GD (2005) The ERECTA gene regulates plant transpiration efficiency in Arabidopsis. Nature 436: 866-870.