Book with abstracts from the COST Action 0905 meeting in ... - UMB
Book with abstracts from the COST Action 0905 meeting in ... - UMB
Book with abstracts from the COST Action 0905 meeting in ... - UMB
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ZN UPTAKE BY WHEAT IN THE PRESENCE OF THE LIGANDS<br />
CITRATE, HISTIDINE OR EDTA<br />
Anja Gramlich 1 , Susan Tandy 1 , Emmanuel Frossard 2 , Ra<strong>in</strong>er Schul<strong>in</strong> 1<br />
1 Institute of Terrestrial Ecosystems, ETH Zurich, Switzerland<br />
2 Institute for Plant, Animal and Agroecosystems Sciences, ETH Zurich, Switzerland<br />
Keywords: Free Zn, Organo-Zn-Complexes, Wheat, Zn Bioavailability<br />
Organic ligands are known to <strong>in</strong>crease <strong>the</strong> mobility of metals <strong>in</strong> soils, but it’s not clear<br />
whe<strong>the</strong>r organo-z<strong>in</strong>c-complexes <strong>in</strong> <strong>the</strong> soil solution can also play a role <strong>in</strong> <strong>the</strong> direct uptake<br />
of z<strong>in</strong>c (Zn) by plants. Us<strong>in</strong>g hydroponic cultures, we <strong>in</strong>vestigated <strong>the</strong> short-term effects of<br />
<strong>the</strong> three ligands citrate, histid<strong>in</strong>e and EDTA on <strong>the</strong> uptake of radio-labeled Zn by wheat,<br />
compar<strong>in</strong>g treatments <strong>with</strong> <strong>the</strong> same free Zn but vary<strong>in</strong>g ligand concentrations. The free Zn<br />
concentration chosen was 50 nM. At this concentration no saturation of Zn <strong>in</strong>flux was observed<br />
<strong>in</strong> a pre-experiment. The required amounts of ligands were calculated us<strong>in</strong>g <strong>the</strong><br />
speciation program MINEQL. In <strong>the</strong> EDTA treatments a Zn flux of 46±3 nmol g -1 root dry<br />
weight h -1 was found. Root Zn uptake and Zn translocation <strong>in</strong>to <strong>the</strong> shoots were enhanced<br />
by a factor of 3-4 <strong>in</strong> <strong>the</strong> presence of citrate and by a factor of 8-9 <strong>in</strong> <strong>the</strong> presence of histid<strong>in</strong>e.<br />
As <strong>the</strong> experiment did not allow to decide whe<strong>the</strong>r <strong>the</strong>se ligand effects on Zn uptake<br />
were due to direct uptake of <strong>the</strong> ligands or due to enhanced transport towards <strong>the</strong> roots, a<br />
second experiment <strong>with</strong> double label<strong>in</strong>g of Zn and ligands was carried out. The samples<br />
are currently analyzed, and <strong>the</strong> results will be presented at <strong>the</strong> conference.