Manganese in Soils and Plants

Sixty years ago at the Waite Agricultural Research Institute, G. Samuel, a plant pathologist, and C. S. Piper, a chemist, published their conclusion that the cause of roadside take-all, a disease of oats, was manganese deficiency. This report, together with the concurrent and independent studies of W. M. Carne in Western Australia were the first records of manganese deficiency in Australia and came only six years after McHargue's paper which is generally accepted as the final proof of the essentiality of this element. There must have been a few doubts for some people at the time, however, as the CAB publication, 'The Minor Elements of the Soil' (1940) expressed the view that further evidence to this effect was provided by Samuel and Piper. Their historic contributions are recognised by the International Symposium on Manganese in Soils and Plants as it meets on the site of their early labours to celebrate the 60th anniversary. This year Australians also acknowledge 200 years of European settlement in this country and so the Symposium is both a Bicentennial and a diamond jubilee event which recognises the impact of trace elements on agricultural development in Australia. In a broader sense, a symposium such as this celebrates, as it reviews, the efforts of all who over the ages have contributed to our knowledge of manganese in soils and plants.

Historical Preface.- 1. An Introduction to Manganese Biological Chemistry.- 1. Introduction.- 2. Manganese chemistry.- 3. The biological chemistry of Mn.- 4. Summary.- Manganese in Soils.- 2. Geochemistry of Manganese in Soil.- 1. Introduction.- 2. The crystal chemistry of Mn.- 3. Manganese in rock-forming minerals.- 4. Manganese in soils.- 5. Conclusions.- 3. Inorganic Reactions of Manganese in Soils.- 1. Introduction.- 2. Solubility relationships of Mn solid phases.- 3. Forms of Mn in soil solution.- 4. Surface reactions.- 5. Fertilizer reactions.- 4. Manganese Redox Reactions and Organic Interactions in Soils.- 1. Introduction: Mn, key to life.- 2. Soil Mn redox methods.- 3. pH and pe.- 4. Reverse dismutation of Mn.- 5. Electron demand and net oxidation studies.- 6. Manganese(III) catalysis and free radicals.- 7. Contributions of components of the living soil.- 8. Manganese mediation of soil N transformations.- 9. Role of Mn in formation of humic polymers.- 5. The Biology of Manganese Transforming Microorganisms in Soil.- 1. Introduction.- 2. Ecology.- 3. Taxonomy.- 4. Physiology and biochemistry.- 5. Conclusions.- 6. Determination of Plant-available Soil Manganese.- 1. Introduction.- 2. Plant factors in soil Mn availability.- 3. Soil Mn.- 4. Soil tests for plant available Mn.- 5. Available soil Mn.- 6. Conclusions.- Manganese in Plants.- 7. The Uptake and Translocation of Manganese by Plant Roots.- 1. Introduction.- 2. The nature of the supply of Mn to the root surface.- 3. Electrochemical considerations.- 4. Kinetics of Mn2+ uptake.- 5. Metabolic dependence of Mn2+ uptake.- 6. Interactions between the uptake and translocation of Mn2+ and other ions.- 7. Uptake rates compared with growth requirement for Mn.- 8. Concluding remarks.- 8. Distribution and Movement of Manganese in Plants.- 1. Introduction.- 2. Movement of Mn in plants.- 3. Distribution of Mn in plants.- 4. Conclusions.- 9. The Biochemistry of Manganese in Plants.- 1. Introduction.- 2. Manganese in proteins.- 3. Manganese as a cofactor.- 4. C4 photosynthesis.- 5. Concluding remarks.- 10. Physiological Functions of Manganese in Plants.- 1. Introduction.- 2. Growth physiology of Mn.- 3. Environmental interactions with Mn.- 4. Manganese in metabolism.- 5. Future directions.- 11. The Role of Manganese in Disease Resistance.- 1. Introduction.- 2. Effect of disease on Mn.- 3. Effect of Mn on disease.- 4. Mechanisms of disease control with Mn.- 5. Conclusions.- 12. The Physiology of Manganese Toxicity.- 1. Introduction.- 2. Manganese toxicity symptoms.- 3. Factors affecting Mn tolerance levels of plant tissues.- 4. Relationships between toxicity symptoms and physiological effects of high Mn concentrations in plant tissues.- 5. Physiology of differential Mn tolerance.- 6. Summary and conclusions.- Manganese in Soil-Plant Systems.- 13. Mechanisms of Manganese Acquisition by Roots from Soils.- 1. Introduction.- 2. Plant and soil factors in absorption.- 3. Dynamics of Mn at the soil-root interface (rhizosphere).- 4. Conclusions.- 14. Occurence and Correction of Manganese Deficiency in Plants.- 1. Introduction.- 2. Occurrence of Mn deficiency.- 3. Prevention and correction of Mn deficiency.- 4. Conclusions.- 15. Manganese Fertilizers.- 1. Introduction.- 2. The chemistry of Mn sources.- 3. Incorporation of Mn into macro-nutrient fertilizers.- 4. Conclusions.- 16. Detection of Manganese Deficiency and Toxicity in Plants.- 1. Introduction.- 2. Diagnosis of Mn deficiency.- 3. Prognosis of Mn deficiency.- 4. Diagnosis of Mn toxicity.- 5. Conclusions.- 17. Genotypic Differences in Tolerance to Manganese Deficiency.- 1. Introduction.- 2. The agronomic case for breeding for Mn efficiency.- 3. Genotypic differences in tolerance to Mn efficiency.- 4. Genetics of Mn efficiency.- 5. Mechanisms of Mn efficiency.- 6. Screening techniques for identifying Mn-efficient genotypes.- 7. Conclusions.- 18. Distribution and Amelioration of Manganese Toxic Soils.- 1. Introduction.- 2. The global distribution of Mn toxic soils.- 3. The development of Mn toxic soils.- 4. The amelioration of Mn toxic soils.- 5. Conclusions.- 19. Genetics and Breeding of Plants Tolerant of Manganese Toxicity.- 1. Introduction.- 2. Examples of differential tolerance.- 3. Breeding for Mn tolerance.- 4. Development and use of Mn tolerant germplasm.- 5. Physiology of differential Mn tolerance.- 7. Conclusions.- 20. Techniques for Research on Manganese in Soil-Plant Systems.- 1. Introduction.- 2. Solution culture systems.- 3. Seed reserves of Mn.- 4. Manganese oxides as sources of Mn.- 5. Analysis and detection of Mn in soils and plants.- 6. Soil preparation and pot culture.- 7. Fractionation procedures.- 21. Manganese in Soils and Plants — An Overview.- 1. Introduction.- 2. Reactions of Mn in soils and plants.- 3. Diagnosis and correction of Mn deficiency and toxicity.- 4. Conclusion.- Glossary of Plant Names.