tailieunhanh - 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. | 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 Microorganisms and Lower Algae .500 Fungi .501 Moss .501 Higher Plants .501 Uptake and Absorption as Related to Properties of Plants .502 Absorption as Related to Properties of Accumulation as Related to the Rhizosphere .503 Cobalt Metabolism in Plants .504 Effect of Cobalt in Plants on Animals .505 Interaction of Cobalt with Metals and Other Chemicals in Mineral Iron .506 Zinc .506 Cadmium .506 Copper .506 Manganese .507 Chromium and Tin .507 Magnesium .507 Sulfur .507 Nickel .507 Cyanide .507 Beneficial Effects of Cobalt on Plants .507 Senescence .507 Drought Resistance .507 Alkaloid Accumulation .507 Vase Life .508 Biocidal and Antifungal Activity .508 Ethylene Biosynthesis .508 499 6 30 2006 1 44 PM Page 500 500 Handbook of Plant Nutrition Nitrogen Fixation .508 Cobalt Tolerance by Plants .508 Algae .508 Fungi .509 Higher Plants .509 References .509 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 .