Root exudates of tomato and spinach enhance uptake of Cu and Zn in resin buffered nutrient solutions
We used resin (Chelex)-buffered nutrient solutions to elucidate the role of root exudates on uptake of Cu and Zn by dicotyledonous plants (tomato and spinach). The resin buffered the free ion activities of Cu2+ and Zn2+ at preset levels (range for pCu: 12.3-10.6, for pZn: 10.1-8.0). The metal concentrations in solution increased during plant growth. This was not observed in plant-free control solutions, indicating mobilization of the metals from the resin by plant- borne organic ligands. At constant pCu, Cu concentrations in solution increased with decreasing Zn supply;while Zn concentrations (at constant pZn) were larger at lower Cu supply. Plant concentrations of Cu and Zn correlated well with solution concentrations. The observed uptake flux of Cu and Zn was larger than the (estimated) maximal diffusion flux of the free metal ion, suggesting that the complexes contribute to diffusion flux and plant uptake. This enhanced diffusion may explain the observed increase in Cu and Zn uptake with increasing soluble metal at constant free ion activity, which is in contrast with the free ion activity model.
copper zinc metal uptake diffusion limitations root exudates
F. Degryse S. Scheerlinck E. Smolders
Division of Soil and Water Management, K. U. Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium
国际会议
第九届痕量元素生物地球化学国际会议(9th International Conference on the Biogeochemistry of Trace Elements)
北京
英文
688-689
2007-07-15（万方平台首次上网日期，不代表论文的发表时间）