1. A Multichannel System for Steady-State and Continuous Measurements of Gas Exchanges from Legume Roots and Nodules.- 1. Introduction.- 2. Overview of the Gas Exchange System.- 3. Application of the Gas Exchange System to Studies of Legume Physiology.- 4. Conclusions.- 2. Quantification of Diffusion Characteristics in Spherical Nodules: A Comparison of Methods.- 1. Introduction.- 2. Homogeneous Model of Nodule Diffusion.- 3. Diffusion Barrier Models.- 4. Comparisons Among Diffusion Barrier Models.- 5. Conclusions.- 6. Appendix. Sensitivity of Transient Analysis to Changes in Vmx.- 3. Simple Apparatus for Growth of Nodulated Plants and for Continuous Nitrogenase Assay Under Defined Gas Phase.- 1. Introduction.- 2. Apparatus — Plant Growth in Defined O2 Levels.- 3. Apparatus — Assays in Open, Flow-Through Systems.- 4. Continuous Measurements of Nitrogenase Activity in the Study of Environmental Responses of Frankia and Other Bacteria.- 1. Introduction.- 2. Materials and Methods.- 3. Results.- 4. Discussion.- 5. Limitations and Errors in Gas Exchange Measurements with Legume Nodules.- 1. Introduction.- 2. Sources of Error.- 3. Avoidance of the Acetylene-Induced Decline.- 4. Conclusions.- 6. Principles and Approaches in Modeling Steady-State Gas Diffusion in Legume Nodules.- 1. Introduction.- 2. General Diffusion Models.- 3. A Model of Gas Diffusion in Legume Nodules.- 4. Other Models of Gas Diffusion.- 7. Modeling Gas Exchange by Actinorhizal Root Nodules Using Network Simulation Analysis.- 1. Introduction.- 2. Model Construction.- 3. Simulation Model Output.- 4. Conclusions.- 8. Continuous and Steady-State Nutrient Absorption by Intact Plants.- 1. Introduction.- 2. Nutrient Flow System.- 3. Ion-Selective Electrodes.- 4. Measurement Artifacts.- 5. Validity ofContinuous and Steady-State Measurements.- 9. Steady-State Control and Investigation of Root System Morphology.- 1. Introduction.- 2. Overview.- 3. Environmental Factors which Affect Roots.- 4. Aeroponics.- 5. Conclusion.- 10. Measurement of Carbon Cost in Ectomycorrhizae.- 1. Introduction.- 2. Carbon Cost as Loss of Potential Dry Matter.- 3. Carbon Flow from Shoot to Root.- 4. Carbon Flow from Root to Fungus.- 5. Modeling Carbon Flow in Ectomycorrhizae.- 6. Conclusions.- 11. Approaches to Measuring Soil Nitrogen Transformations Under Continuous or Steady-State Conditions.- 1. Introduction.- 2. The Soil Environment.- 3. Soil Nitrogen Transformations.- 4. Continuous and Steady-State Terminology.- 5. Laboratory Methods.- 6. Field Methods.- 7. Isotope Dilution.- 8. Summary.- 12. Methodological Considerations in Measuring Biomass, Production, Respiration and Nutrient Resorption for Tree Roots in Natural Ecosystems.- 1. Introduction.- 2. Problems Associated with Field Root Studies.- 3. Root Biomass and Production.- 4. Root Respiration.- 5. Root Resorption of Nutrients.- 6. Conclusions.- Authors’ Index.