Cobalt distribution in several pasture species grown in culture solutions

Abstract

Lucerne (Medicago sativa cv. Hunter River), subterranean clover (Trifolium subterraneum L. cv. Bacchus Marsh), prairie grass (Bromus catharticus Vahl), Phalaris tuberosa, and evening primrose (Oenothera sp.) were grown in culture solutions containing ⁶⁰Co. The distribution of cobalt in the tops was determined with autoradiographs of pressed, rapidly dried plants and by measuring the total amounts of ⁶⁰Co in pieces of fresh leaves dissected immediately after harvesting.

Cobalt concentrations in the margins of lucerne, clover, and primrose leaves and at the base and extreme tip of the primrose and grass leaves were many times those found in other parts of the leaves. Cobalt accumulated at cut and cropped ends of leaves. Leaching removed up to 75% of the cobalt from dried leaves but none from fresh leaves. The concentration of cobalt in a given lucerne leaf reached a maximum soon after emergence and then declined rapidly as the leaf expanded.