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Handbook of Plant Nutrition - chapter 17

17 Cobalt Cobalt has long been known to be a micronutrient for animals, including human beings, where it is a constituent of vitamin B12 (1). However, its presence and function has not been recorded to the same extent in higher plants as in animals. | CRC_DK2972_Ch017.qxd 6 30 2006 1 44 PM Page 499 17 Cobalt Geeta Talukder Vivekananda Institute of Medical Sciences Kolkata India Archana Sharma University of Calcutta Kolkata India CONTENTS 17.1 Introduction.500 17.2 Distribution.500 17.2.1 Microorganisms and Lower Plants.500 17.2.1.1 Algae .500 17.2.1.2 Fungi .501 17.2.1.3 Moss .501 17.2.2 Higher Plants .501 17.3 Absorption.502 17.4 Uptake and Transport.502 17.4.1 Absorption as Related to Properties of Plants .502 17.4.2 Absorption as Related to Properties of Soil.503 17.4.3 Accumulation as Related to the Rhizosphere .503 17.5 Cobalt Metabolism in Plants .504 17.6 Effect of Cobalt in Plants on Animals .505 17.7 Interaction of Cobalt with Metals and Other Chemicals in Mineral Metabolism.505 17.7.1 Iron .506 17.7.2 Zinc .506 17.7.3 Cadmium .506 17.7.4 Copper .506 17.7.5 Manganese .507 17.7.6 Chromium and Tin .507 17.7.7 Magnesium .507 17.7.8 Sulfur .507 17.7.9 Nickel .507 17.7.10 Cyanide .507 17.8 Beneficial Effects of Cobalt on Plants .507 17.8.1 Senescence .507 17.8.2 Drought Resistance .507 17.8.3 Alkaloid Accumulation .507 17.8.4 Vase Life .508 17.8.5 Biocidal and Antifungal Activity .508 17.8.6 Ethylene Biosynthesis .508 499 CRC_DK2972_Ch017.qxd 6 30 2006 1 44 PM Page 500 500 Handbook of Plant Nutrition 17.8.7 Nitrogen Fixation .508 17.9 Cobalt Tolerance by Plants .508 17.9.1 Algae .508 17.9.2 Fungi .509 17.9.3 Higher Plants .509 References .509 17.1 INTRODUCTION Cobalt has long been known to be a micronutrient for animals including human beings where it is a constituent of vitamin B12 1 . However its presence and function has not been recorded to the same extent in higher plants as in animals leading to the suggestion that vegetarians and herbivorous animals need to ingest extra cobalt or vitamin B12 in diets to prevent deficiency. Vitamin B12 is synthesized in some bacteria but not in animals and plants 1 . Intestinal absorption and subsequent plasma transport of vitamin B12 are mediated by specific vitamin .