Abstract
Aims
Root elongation tests are sensitive bioassays for testing metal toxicity in nutrient solutions. The metal speciation and, hence, metal exposure conditions are little controlled in the traditional set-up. A resin buffered solution system was developed to overcome this issue.
Methods
Barley (Hordeum vulgare L.) root elongation was tested in aerated 140 mL solution batch systems supplied with 3.3 g Dowex resin for two plants. Copper toxicity was measured in presence or absence of the resin (+R/−R) and in presence or absence of a metal complexing ligand (+NTA; nitrilotriacetic acid/−NTA). In addition, the toxicity in the traditional set without resin and with daily solution replacement was included as a reference.
Results
Metal desorption from the resin is fast in these systems (k = 0.82 h−1). Total dissolved Cu roughly halved during 4 days in −R/−NTA systems due to uptake, while it increased by 30 % in the +R/−NTA, probably due to complexation reactions by root-derived molecules. The toxicity (50 % reduction in root length, EC50) of the initial free Cu2+ was equal in all resin or chelate buffered systems and in the solutions with daily replacement, whereas this threshold was significantly larger in the −R/−NTA due to Cu2+ uptake and complexation reactions.
Conclusion
The resin method is a convenient system for high throughput screening of metal toxicity and avoids uncertainties in metal speciation inherent to chelator buffered systems. Details are given how to prepare the resin to obtain a target metal ion activity.
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The authors thank the Fund for Scientific Research - Flanders (FWO) for financial support (project FWOG0460.12).
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Responsible Editor: Erik J. Joner.
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Versieren, L., Smets, E. & Smolders, E. A resin buffered method for controlling metal speciation in nutrient solutions for plant toxicity tests. Plant Soil 373, 257–267 (2013). https://doi.org/10.1007/s11104-013-1797-7
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DOI: https://doi.org/10.1007/s11104-013-1797-7