Translocation of Manganese in Subterranean Clover (Trifolium subterraneum L. Cv. Seaton Park) I. Redistribution During Vegetative Growth

Abstract

The mobility of manganese from old leaves and cotyledons during vegetative growth has been examined by following manganese content and radioactive manganese redistribution in parts of subterranean clover plants grown into manganese deficiency.

In plants transferred from nutrient solutions with 1 µM Mn²⁺ to solutions without Mn²⁺, the amount of manganese in the roots decreased markedly. During the same period there was no net loss of manganese from cotyledons and old leaves, although plants developed severe manganese deficiency symptoms in young leaves.

Old leaves of plants given an early supply of ⁵⁴Mn lost no ⁵⁴Mn when the plants were transferred to non-radioactive solutions without manganese for 14 days. Silicon, which is known to influence the distribution of manganese within leaves of some plants, had no effect on the loss of total manganese or ⁵⁴Mn from old leaves.

Detached green, mature leaves lost 40% of their manganese within 24 h when aerated in water. If leaching by rain removes substantial amounts of manganese from leaves of plants grown in the field, this may account for reports of manganese mobility in plant phloem. The present results establish that manganese is not mobile in the phloem of subterranean clover plants during vegetative growth.