During the past three decades there has been a large amount of research on biological nitrogen fixation, in part stimulated by increasing world prices of nitrogen-containing fertilizers and environmental concerns. In the last several years, research on plant--microbe interactions, and symbiotic and asymbiotic nitrogen fixation has become truly interdisciplinary in nature, stimulated to some degree by the use of modern genetic techniques. These methodologies have allowed us to make detailed analyses of plant and bacterial genes involved in symbiotic processes and to follow the growth and persistence of the root-nodule bacteria and free-living nitrogen-fixing bacteria in soils. Through the efforts of a large number of researchers we now have a better understanding of the ecology of rhizobia, environmental parameters affecting the infection and nodulation process, the nature of specificity, the biochemistry of host plants and microsymbionts, and chemical signalling between symbiotic partners. This volume gives a summary of current research efforts and knowledge in the field of biological nitrogen fixation. Since the research field is diverse in nature, this book presents a collection of papers in the major research area of physiology and metabolism, genetics, evolution, taxonomy, ecology, and international programs.

Our knowledge of the biochemistry and biophysics of dinitrogen fixa tion has developed rapidly in the 15 years since the first N2-fixing enzyme system was successfully extracted from a bacterium. This peri od has produced a literature that now describes the N2 fixation reac tion and the nitrogenase enzyme itself in sophisticated terms, though a detailed reaction mechanism at the chemical level has not yet emerged. It is the purpose of the present monograph to present an in-depth re view, analysis, and integration of this research as is possible with a non-contributed publication and to relate this work to considera tions of N2 fixation that reach beyond the confines of the biochem ist's laboratory. The first section is directed as much toward the general science read er as toward the specialist. It covers the agricultural origins of man's interest in N2 fixation and also pertinent areas of taxonomy, physiology, and evolution. Ecological aspects of the subject include a comprehensive evaluation of the nitrogen cycle leading to a sub stantially greater estimate of the rate of global N2 fixation than previous ones. The treatment is of a survey fashion, in part to pro vide a general over-view of N2 fixation and in part to provide context for the biochemistry and biophysics that follow in the second section.

This self-contained volume covers fundamental and applied aspects of nitrogen-fixation research. The book describes milestones in the discovery of the associative and endophytic nitrogen-fixing bacteria found involved with cereal crops, forage grasses, and sugar cane. It provides a comprehensive overview of their phylogeny, physiology, and genetics as well as of the biology of their association with their host plants, including tools for in situ localization and population-dynamics analysis. Also included are chapters describing the functions required for a bacterium to be competent and competitive in the rhizosphere, and analysis of associations of cyanobacteria with fungi, diatoms, bryophytes, cycads, Azolla, and Gunnera.

Biological nitrogen fixation has essential role in N cycle in global ecosystem. Several types of nitrogen fixing bacteria are recognized: the free-living bacteria in soil or water; symbiotic bacteria making root nodules in legumes or non-legumes; associative nitrogen fixing bacteria that resides outside the plant roots and provides fixed nitrogen to the plants; endophytic nitrogen fixing bacteria living in the roots, stems and leaves of plants. In this book there are 11 chapters related to biological nitrogen fixation, regulation of legume-rhizobium symbiosis, and agriculture and ecology of biological nitrogen fixation, including new models for autoregulation of nodulation in legumes, endophytic nitrogen fixation in sugarcane or forest trees, etc. Hopefully, this book will contribute to biological, ecological, and agricultural sciences.

Jointly published with INRA, Paris. This book covers all aspects of the transfer of nitrogen from the soil and air to a final resting place in the seed protein of a crop plant. It describes the physiological and molecular mechanisms of ammonium and nitrate transport and assimilation, including symbiotic nitrogen fixation by the Rhizobiacea. Amino acid metabolism and nitrogen traffic during plant growth and development and details of protein biosynthesis in the seeds are also extensively covered. Finally, the effects of the application of nitrogen fertilisers on plant growth, crop yield and the environment are discussed. Written by international experts in their field, Plant Nitrogen is essential reading for all plant biochemists, biotechnologists, molecular biologists and physiologists as well as plant breeders, agricultural engineers, agronomists and phytochemists.

Long-awaited second edition of classic textbook, brought completely up to date, for courses on tropical soils, and reference for scientists and professionals.