Zinc uptake and distribution in ivy (Hedera helix L.) leaves

Detached leaves of ivy (Hedera helix L.) were used as a model for the study of zinc uptake and transport in vascular plants. By the uptake via the surface of fully immersed leaves in 25 % Hoagland nutrient media (HM) spiked with 65ZnCl2 (50 μmol/dm3 ZnCl2), concentration in leaves 4.98 μg Zn/g (dry wt.), i. e. 2.6 μg Zn/dm2 leaf area after 7d exposition were obtained. By the uptake via immersed stalks of not immersed (transpiring) leaves concentrations up to 370 μg Zn/g (dry wt.) were obtained. When Zn enters into detached leaves via the surface of immersed leaf blades, zinc is uniformly distributed in leaf blades and leaf stalks. When zinc enters detached leaves via immersed stalks of non-immersed transpiring leaves, only small part of zinc is transported to leaf blades and the prevailing part remains in leaf stalks. Stalks act as a trap, able to prevent other leaf tissues against inhibitory effects of high Zn concentrations. Mineral nutrient salts in solutions mobilize Zn trapped in leaf stalks and facilitate Zn transport by transpiration stream to leaf blades, what means that Zn in stalks is bound in ion-exchageable forms.