Translocation of Manganese in Subterranean Clover (Trifolium subterraneum L. Cv. Seaton Park). II. Effect of Leaf Senescence and of Restricting Supply of Manganese to Part of a Split Root System

Abstract

Split root systems were used to examine the hypothesis that manganese is not mobile in the phloem of subterranean clover plants during vegetative growth. The effect of senescence on manganese mobility was also examined by shading mature leaves. Plants given a luxury supply of radioactive manganese to one half of a split root system failed to translocate any more than a trace of manganese to the other half. Shading and subsequent senescence of a large number of leaves did not cause movement of manganese from them. Omitting an external supply of manganese depressed growth of roots but produced no visual abnormalities even though Mn concentrations decreased to 5 µg/g dry matter of root.