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Handbook of Plant Nutrition - chapter 14

14 Nickel Nickel (Ni), the most recently discovered essential element (1), is unique among plant nutrients in that its metabolic function was determined well before it was determined that its deficiency could disrupt plant growth. | CRC_DK2972_Ch014.qxd 6 30 2006 3 31 PM Page 395 14 Nickel Patrick H. Brown University of California Davis California CONTENTS 14.1 Introduction .395 14.2 Discovery of the Essentiality of Nickel .396 14.3 Physical and Chemical Properties of Nickel and Its Role in Animal and Bacterial Systems.397 14.3.1 Nickel-Containing Enzymes and Proteins .397 14.3.2 Essentiality and Function of Nickel in Plants .398 14.3.3 Influence of Nickel on Crop Growth .400 14.4 Diagnosis of Nickel Status.401 14.4.1 Symptoms of Deficiency and Toxicity.401 14.5 Concentration of Nickel in Plants .403 14.6 Uptake and Transport.404 14.7 Nickel in Soils .404 14.7.1 Nickel Concentration in Soils .404 14.7.2 Nickel Analysis in Soils .405 14.8 Nickel Fertilizers .405 14.9 Conclusion .406 References .406 14.1 INTRODUCTION Nickel Ni the most recently discovered essential element 1 is unique among plant nutrients in that its metabolic function was determined well before it was determined that its deficiency could disrupt plant growth. Subsequent to the discovery of its essentiality in the laboratory Ni deficiency has now been observed in field situations in several perennial species 2 . The interest of plant scientists in the role of nickel was initiated following the discovery in 1975 3 that it was a critical constituent of the plant enzyme urease. The ultimate determination that nickel was essential for plant growth 1 depended heavily on the development of new techniques to purify growth media and to measure extremely low concentrations of nickel in plants. The establishment of nickel as an essential element however highlights the limitations of the current definition of essentiality of nutrients as applied to plants 4 . It has been argued for example that even though nickel is clearly a normal and functional constituent of plants it does not fulfill the definition of essentiality since urease is not essential for plant growth and nickel deficiency apparently does not prevent the completion of the .