Symbiotic N2 Fixation of Crop Legumes Achievement and Perspectives

About this book

The conversion of nitrogen gas to nitrogen compounds (N₂ fixation) is essential for living organisms, and can be facilitated by industrial and natural processes. A major proportion of the naturally "fixed" nitrogen is biologically converted by micro-organisms living in symbiosis with plants. Legumes represent common hosts for a range of such diazotrophic bacteria, and constitute, next to cereals, the most important agricultural crops. Starting with first principles, this book provides wide-ranging, up-to-date information on symbiotic N₂ fixation of legumes with emphasis being placed upon common bean (phaseolus vulgaris) and soybean (glycine max). Divided into five chapters, the text focuses – after an initial introduction – on processes leading to nodulation and maturation of nodules, biochemical and physiological aspects of N₂ fixation, as well as the influence of the environment on symbiotic activity. Following chapters deal with techniques used for laboratory and field measurements of N₂ fixation, specific physiological aspects of supernodulating legumes, and future perspectives for increasing symbiotic conversion of dinitrogen in agricultural systems. The text gives a comprehensive overview of current theory and practice of the subject. It should be useful for graduate students, and represents a reference for scientists engaged in studies on symbiotic N₂ fixation.

Contents

- Introduction: atmospheric N₂
- non-biological forms of N₂ fixation
- biological forms of N₂ fixation
- N₂ fixation in natural ecosystems
- N₂ fixation in forestry and recultivation
- N₂ fixation in agriculture

Part 1 N₂ fixation of leguminosae
- the microsymbiont
- the macrosymbiont
- nodulation
- different forms of nodules
- metabolism of N₂ fixation
- influence of the environment

Part 2 Assessment techniques for N₂ fixation
- direct methods
- indirect methods

Part 3 Supernodulating legumes
- symbiotic performance and the effect of nitrate
- carbon and nitrogen metabolism

Part 4 Means to improve N₂ fixation
- current approaches
- potential for future benefits

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