Effects of Chelation and of Various Cations on the Mobility of Foliar-Applied 65zn in Subterranean Clover

Abstract

SummaryInjection of 65Zn of high specific activity into old leaves of subterranean clover (Trifolium 8ubterraneum L.) resulted in the virtual immobilization of the isotope in the laminae of the treated leaves. The addition of 30, 300, or 500 p.g respectively of non-radioactive zinc to the dose resulted in progressively increased ,movement of 65Zn into other parts of the plant.Movement of 65Zn from the injected leaf was also enhanced by the addition to the dose of either EDTA or one of various cations in amounts equivalent to 500 p.g Zn. This enhancement was comparable with that induced by 500 p.g Zn with EDTA, Cu2+, Mn2+, and Fe2+; intermediate with Mg2+ and Ca2+; and least with Na+ andK+.It is concluded that non-selective negatively charged sites of fixation occur in the leaf of subterranean clover.

Movement of Previously Deposited 45ca in Subterranean Clover (Trifolium Subterraneum l.) by Foliar Injections of Certain Cations

“…One corollary which appears implicit in these results is that those ions which were active in displacing calcium are themselves subject to movement and displacement in quite the same way as calcium itself. Millikan and Hanger (1965b) have postulated the occurrence of non-selective negatively charged sites of fixation in subterranean clover. Evidently there is mutual displacement of cations on such sites within the tissue, subject presumably, like all such reactions, to the effects of mass action and the position of the cation in the lyotropic series.…”

The Mobility of 65zn In Trifolium Subterraneu M L. and Antirrhinum Majus L.

“…The foliar injection of 1000 fLg of non-radioactive zinc (an amount sufficient to ensure its movements throughout the plant; Millikan and Hanger 1965b) into T. subterraneum also failed to induce movement of 65Zn out of any leaves. However, the injections did cause some recirculation of 65Zn within leaves, but apparently only in an acropetal direction.…”

“…Clare) and tetraploid snapdragon (A. majus) were grown in water cultures. The composition of the complete nutrient culture and the procedure used for autoradiographing and radioassaying the plant tissue are identical to those described by Millikan and Hanger (1964, 1965a, 1965b.…”