This paper analyzes the effect of caesium (Cs) concentration on seed germination, seedling growth, root uptake, and leaf uptake of Lactuca sativa to understand the potential transfer of the metal from contaminated soil to humans through the food chain. The results of germination experiments show that seed germination and seedling growth strongly depend on increasing Cs concentration, with a decrease in the number of germinated seeds compared to the control up to 13.6% and a reduction in seedling growth up to 10.3% at the highest Cs tested concentration (15 mM). Uptake experiments indicate a low transfer of Cs from soil to leaves and roots of the plants, ranging between 0.06% and 2.2%. The transfer is found to be a not-monotone function of soil potassium (K) content, with highest values corresponding to 1-2 mM K2SO4. Increasing concentrations of K lead to lower translocation of Cs from roots to leaves. Values above the average amount applied (20 and 40 mM K2SO4) almost stop the translocation, suggesting the use of a high amount of K2SO4 protects the food chain from Cs contamination.

Czech University of Life Sciences Prague Faculty of Environmental Sciences Kamýcká 129 165 21 Prague 6 Czech Republic

Department of Civil and Mechanical Engineering University of Cassino and Southern Lazio via di Biasio 43 03043 Cassino Italy

University of Naples Federico 2 Department of Civil Architectural and Environmental Engineering Via Claudio 21 80125 Napoli Italy

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