U.S.-Australia Cooperative Research: A Study of the Effect of Soil Nitrogen on Water-Use Efficiency in Eucalypts from Contrasting Habitats (Long-Term Visit)

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This award will support a Long-Term Research Visit to the Australian National University (ANU) by Professor Jay E. Anderson, Department of Biological Sciences, Idaho State University. The visit takes place under the U.S.-Australia Cooperative Science Program. While in Australia, Professor Anderson will collaborate with Professor Graham D. Farquhar, Research School of Biological Sciences, ANU, and Dr. Michael P. Austin, Commonwealth Scientific and Industrial Research Organization (CSIRO). The objectives of the project are (1) to determine whether the observed distributions of three species of Eucalyptus in southeastern Australia are related to differences in the efficiency with which the different species use water, and (2) to resolve whether variation in water use efficiency among species results from inherent differences in photosynthetic or other physiological processes (including stomatal) involving the leaf, or whether differences in ability to acquire nutrients, especially nitrogen, from the soil are responsible. The results are relevant to agricultural and silvicultural selection programs aimed at identifying plant species and genotypes that are superior in water use efficiency, as well as to efforts to understand mechanisms that underlie the natural distribution of species. Professor Anderson will carry out this research while on sabbatical leave from Idaho State University. He will study eucalypts in Australia subjected to gradients in mean annual temperature and in mean annual rainfall. The effect of nitrogen level on plant growth, photosynthetic capacity, stomatal conductance, carboxylation efficiency, water use efficiency, and nitrogen use efficiency will be studied. Both the U.S. and Australian groups have experience in this area of research. Previous work by Professor Anderson and his group in Idaho has shown that nitrogen fertilization improves water use efficiency among native species. Professor Farquhar and his colleagues at ANU have been responsible for many advances in the understanding of the efficiency of water use by plants, and have provided both theoretical models and empirical evidence relating carbon isotope discrimination in the photosynthetic process to water use efficiency. Dr. Austin, of CSIRO's Division of Wildlife and Ecology, is a leading international vegetation scientist who has studied eucalypt distributions in gradients of temperature and rainfall. Experimental facilities at ANU, including an analytical laboratory for performing isotopic and other analyses, will greatly facilitate the carrying out of this research project.