Genetic Engineering Of Symbiotic Nitrogen Fixation And Conservation Of Fixed Nitrogen

There is a time in scientific research when a number of developments coincide making it possible to progress with a tough and complicated problem. It is believed that such a time has come in the area of biological nitrogen fixation. A better understanding of photosynthesis, cell hybridization, plasmid, and gene transfer between cells not necessarily genetically related, have opened new avenues of research. New developments in traditional genetics, cell biology, biochemistry, including enzyme chemistry, and plant physi ology have brought about the feeling this is a most appro priate time to pull together the different approaches in a conference where the lines of research could be discussed and thus help to speed up developments in this area. What makes biological nitrogen fixation especially im portant is the promise that a good understanding of the basic problem would help us to make organisms more amenable to fix nitrogen, not only in symbiosis with legumes, but also with other plant species and develop a wider variety of organisms with the ability to fix N • It will also 2 encourage a search for naturally occurring N2 fixing organ isms other than the traditional N2 fixers. Some success has already been encountered in this area. Success in broadening the field of nitrogen fixing would help to increase food supply, especially in de veloping countries which cannot afford to purchase synthetic nitrogen sources.

The present volume developed from a symposium entitled "Enhancing Biological Production of Ammonia From Atmospheric Nitrogen and Soil Nitrate" that was held at Lake Tahoe, California in June, 1980. The meeting was supported by the National Science Foundation, Division of Engineering and Applied Sciences and by the College of Agricultural and Environmental Sciences, University of California, Davis. A total of 99 scientists from 41 insti tutions participated. Plants capture solar energy in photosynthesis and use mineral nutrients to produce human food and fiber products. The extent to which such materials are removed from agricultural production sites represents a permanent drain of mineral nutrients. Some plants of agronomic importance such as alfalfa, soybean, and clover associate with soil bacteria and use photosynthetic energy to reduce N2 to NH3. Many other free-living bacteria and some symbioses involving procaryotes and eucaryotes also reduce N2. Such processes repre sent one natural mechanism by which Man can augment soil N for agronomic purposes without using fossil fuel to synthesize and distribute N fertilizer. Other metabolic conversions in the N cycle and physical leaching processes remove N made available through N2 fixation. Thus nitrification, denitrification, and utilization of soil N by plants are processes that must be con sidered if one is to conserve N captured by N2 fixation. The meeting at Lake Tahoe united scientists from many disci plines to review the literature and to discuss current research directed toward the goal stated in the symposium title.

In one convenient source, this ready reference brings together for the first time, all the information available on various cyanobacterial symbioses/symbiotic cyanobacteria. Comprehensive data on structure, physiology, biochemistry and molecular biology of the cyanobiont in various cyanobacterial symbioses is included. Aplied aspects such as use of Azolla in rice cultivation and artificial symbioses are addressed, along with a chapter dedicated to methodology. This informative new text is useful to researchers, teachers, and students.

An updated edition of the classic work on the inorganic chemistry of soils. * With its companion volume, Humus Chemistry, forms a complete, advanced-level treatment of both organic and inorganic aspects of soil chemistry. * Revised to keep pace with the latest developments in the field. * Provides more in-depth treatment of all topics.

The common bean (Phaseolus vulgaris L.) is the most important pulse crop in Latin America, as well as in large parts of Asia and Africa. It is particularly important due to its ability, in symbiosis with Rhizobium bacteria, to fix atmospheric nitrogen and due to its high nutrient value. Incorporating contributions from plant breeders, microbiologists, plant physiologists and soil scientists, this volume reports the results of an FAO/IAEA Coordinated Research Programme (1985--1991), whose main objective was to enhance yield and biological nitrogen fixation in common bean by reducing its reliance on soil and fertilizer nitrogen. The volume will be invaluable to scientists working on biological nitrogen fixation and legume production.