Relation of Nitrogen Supply to the Molybdenum Requirement of Cauliflower Grown in Sand Culture

Abstract

THE possible need for molybdenum by higher plants supplied with nitrogen in a form other than nitrate was first indicated by Arnon1, who obtained improved growth of barley plants in the presence of a solution containing chromium, molybdenum and nickel with an ammonium nitrogen supply. Vanselow and Datta2 and Hewitt3 later showed the need of molybdenum by plants with adequate ammonium and nitrate nitrogen. Hewitt, however, has stated3 that the absolute need for molybdenum for normal development when higher plants are supplied with ammonium nitrogen only still remains to be shown, and that the experimental difficulties of the use of ammonium compounds alone limit progress. Incorporation of solid calcium carbonate into ammonium nitrogen cultures, however, has been shown greatly to reduce the injury due to ammonium4,5. This device has been successfully applied to molybdenum-deficiency cultures using a purified source of calcium carbonate.