Using a chelate-buffered nutrient solution to establish the critical solution activity of Mn2+ required by barley (Hordeum vulgare L.)

Webb, Michael J.; Norvell, W. A.; Welch, Ross M.; Graham, Robin D.

doi:10.1007/bf00012992

Cited by 21 publications

(1 citation statement)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Shoot concentrations of spinach grown in these solutions were small for Cu (2-4 mg kg -1 DW) and Mn (15-20 mg kg -1 ), which might have caused the yield reduction of spinach in the CDTA treatments (Table 3). Webb et al (1993) estimated a critical Mn 2+ activity of 10 -8.3 M required for barley in nutrient solutions buffered with HEDTA at a 25-lM excess. The free Mn 2+ activity in the CDTA treatments was smaller than this critical value (Table 1) In Experiment 2, shoot and root concentrations of Cu in tomato remained fairly constant among treatments, and hence, total uptake paralleled the dry-matter production (Table 4).…”

Section: Uptake Of Other Micronutrientsmentioning

confidence: 99%

Metal complexes increase uptake of Zn and Cu by plants: implications for uptake and deficiency studies in chelator-buffered solutions

2006

View full text Add to dashboard Cite

The uptake of trace metals by plants is commonly assumed to depend on the free metalion activity, rather than on the total concentration of dissolved metal. Although this free-ion hypothesis has proved to be useful for the interpretation and prediction of metal uptake, several exceptions have been reported where metal complexes also affected metal uptake by plants.In this study, we measured uptake of Zn and Cu by spinach (Spinacia oleracea L.) and tomato (Lycopersicon esculentum L.) in chelator-buffered or resin (Chelex)-buffered solutions, under Zn-deficient and non-deficient conditions. Several ligands, with differing dissociation rates, were used in the chelator-buffered solutions. At the same free-ion activity, Cu and Zn uptake was less in Chelex-buffered than in chelator-buffered solutions. In the chelator-buffered solution, uptake of Cu and Zn at same free-ion activity and same total concentration followed the order: NTA > HEDTA > EDTA > CDTA, i.e., the same order as the dissociation rate. These differences in metal uptake were also reflected in the deficiency symptoms and plant yield in the experiments where Zn deficiency was imposed. The critical Zn 2+ activity for Zn deficiency varied by one order of magnitude depending on the buffer, and followed the order HEDTA < CDTA < resin-buffered (no soluble ligand). These results suggest that, when present, aqueous complexes can increase metal uptake by plants because uptake is rate-limited by diffusion of the free ion to the root or cell surface. Thus, the critical free-ion activity in chelator-buffered solutions depends on the type and concentration of the ligand employed.

show abstract

Section: Uptake Of Other Micronutrientsmentioning

confidence: 99%