Symbiotic Nitrogen Fixation Technology

Collection, isolation and maintenance of Rhizobia and Frankia; Colletion, cultivation and maintenance of azolla; Collection, isolation, cultivation and maintenance of associative N2-fixing bacteria; Fluorescence methods for study of Rhizobium in culture and in situ; Serological techniques for Brabyrhizobium and Rhizobium identification; Enzyme-linked immunosorbent assay (ELISA) for the detection and identification of Rhizobium strains; Use of Intrinsic culture and antibiotic resistance for Rhizobium Study; Isolation and identification of genetically marked strains of nitrogen-fixing microsymbionts of soybens; Measurement of nitrogen fixation by direct means; Measurement of biological fixation using acetylene reduction; Measuring ureides; Evaluation of nitrogen fixation by legumes in the greenhouse and growth chamber; Principles and practice of field designs to evaluate symbiotic nitrogen fixation; Production and quality control of inoculants; Role of culture collectios in biological nitrogen fixation.

The core of the text is aimed at the research worker in the field of nitrogen fixation, but, despite its specialisation, does not lose the emphasis on teaching, both as a direct reference book and as a backbone for a graduate course on the subject.The closing part of the book includes a subject index and a glossary of terms. The latter was included not for the expert, for whom many of the definitions will be too general, but for the newcomer; the author hopes that the quick survey of key terms will help in the reading of this book.

Rhizobium species involved in root nodule formation on legume plants are one of the best known groups of micro organisms. The Rhizobium legume symbiosis continues to be of strategic importance particularly in the context of food production. As the world population grows, it is also neces sary to have new developments taking place in crop improve ment. The development and application of new technologies in biological sciences over the past number of years have made the entire area of plant-microbial interaction an exciting and challenging research area to be involved in. In view of the importance of symbiotic nitrogen fixation, it is not surpris ing that it still represents one of the priority areas for commercial development in agricultural biotechnology. Since this symbiosis involves an association between procaryotic and eucaryotic partners, it requires of necessity a co-ordinated and interdisciplinary approach. It was in this spirit that this international conference was organised. The scientific programme was designed to focus on physio logical limitations affecting symbiotic nitrogen fixation and the potential for overcoming such limitations using genetic technologies. Participants were drawn from contractants of the EEC DGVI "Energy in Agriculture" nitrogen fixation prog ramme. The scientific programme was also supplemented with invited scientists from Europe and North America to provide appropriate expertise on the various conference topics.

The International Workshop on Biological Nitrogen Fixation for Increased Crop Productivity, Enhanced Human Health and Sustained Soil Fertility was held in June 2002 at ENSAM-INRA, Montpellier, France. The main goal of the workshop was to define research strategies for a Challenge Program initiative on Biological Nitrogen Fixation, and develop a pre-proposal based on the concept note submitted and approved by the CGIAR iSC. More than 35 participants from various scientific disciplines, research institutions and from four different continents (Africa, Asia, Americas and Europe) attended the workshop. This book, based on the proceedings of the workshop, takes a holistic approach to harnessing legume BNF technologies, starting from a socioeconomic perspective, and progressing to agronomic and genetic options, and bringing together innovative aspects and participatory research strategies.

In the 100 years since the legume-Rhizobium symbiotic nitrogen fixation interaction was first described, interest in this field has grown rapidly. The types of studies have been cyclical in nature, involving a cross-section of disciplines. The availability of cheap nitrogenous fertilizers caused much of the biological nitrogen fixation research to become more theoretical in the developed world. The high cost of energy, coupled with environmental concerns and the interest in sustainable agriculture, has stimulated research in symbiotic nitrogen fixation. The development of modern genetic techniques has resulted in interdisciplinary research on plant-microbe interactions controlling nitrogen fixation. This has resulted in a better understanding of environmental factors influencing the nodulation process, chemical signalling between the symbiotic partners and the nature of the specificity between host plant and microsymbiotant. This volume summarizes the diverse research efforts in biological nitrogen fixation by presenting a collection of papers in the areas of physiology and metabolism, taxonomy and evolution, genetics and ecology.

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.

Genetical aspects and taxonomy; Quality of legume inoculants; Field experiments on nitrogen fixation by nodulated legumes; Legume nitrogen fixation and the environment; Nitrogen fixing symbioses in non-leguminous plants.