Chemical Forms of Nickel and Cobalt in Phloem of <i>Ricinus communis</i>

Abstract

Abstract Investigations were performed to study the chemical form in which nickel and cobalt are transported in sieve tubes. Ricinus communis plants were used since they allow easy collection of relatively pure phloem sap. In the experiments labelled nickel or cobalt were given to the nutrient solution. The tapped phloem exudate was separated by gel filtration on Sephadex or by paper electrophoresis. Nickel and cobalt were bound to complexing organic compounds with a molecular weight in the range of 1000—5000. The overall charge of the nickel complex was negative, and the bulk of cobalt also appeared to complex to a compound with negative overall charge.