Molecular and Physiological Studies of Nitrogen Uptake by Plants and Fungi

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In order to sustain current high levels of agricultural productivity, global application of nitrogen fertilizers has risen greater than 20 fold since 1950, to a current rate that is approximately 140 million tonnes (140 billion kg) per annum, at a cost of roughly seventy billion dollars U.S. In addition to this economic consideration, another problem is that the bulk of applied N fertilizer is lost through volatilization, denitrification and leaching. For example cereals recover only 30 to 40% of applied nitrogen. Therefore, it has been estimated that a modest 1% increase of N-use efficiency would save 250 million dollars (Raun and Johnson 1999). From an ecological perspective, fertilizer leaching is a major contributor to eutrophication of lakes and coastal waters. In the Gulf of Mexico, e.g. huge areas of coastal waters are now depleted of oxygen causing massive fish kills. Hence, there is every need to improve N-use efficiency. My research seeks to define the processes involved in nitrate fertilizer absorption by plant roots. The transport of nutrients across cell membranes is a process that has been of fundamental interest to both pure and applied scientists since the beginnings of biological study. It continues to be a subject of intense study. From a more applied perspective, only through better comprehension of this fundamental process will it be possible to improve crop yield globally and locally while achieving greater efficiency of plant use of applied fertilizer. The implications, of this research, both economically and environmentally are profound, especialy for developing countries.