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.