The Influence of Zinc Supply to Seedlings of Pinus radiata D. Don on the Internal Transport of Recently Absorbed Zinc

Abstract

The movement of a 48 h pulse of 65Zn supplied to P. radiata seedlings growing in solutions containing varying concentrations of zinc was examined by taking a series of harvests following the application of the pulse. The movement of recently absorbed 65Zn through the stem and into the foliage was slower in plants with a low supply of zinc resulting in a greater accumulation of 65Zn in stems of these plants than in those with a high supply of zinc. Transferring plants from a low supply to a high supply of zinc decreased the quantity of 65Zn in the stem to the levels found in plants grown with a continuously high supply of zinc. Seedlings with a low external supply of zinc distributed more of the recently absorbed 65Zn to their lower needles than to their upper needles, probably as a consequence of the slower movement of zinc through plants with a low zinc supply. The movement of zinc through seedlings of P. radiata was slow even in plants with an adequate supply of zinc. Two weeks after the pulse of 65Zn was applied, 65Zn was still moving from the stem into the foliage.