The phytoextraction power of Cichorium intybus L. on metal-contaminated soil: Focus on time- and cultivar-depending accumulation and distribution of cadmium, lead and zinc

Abstract

This study is focused on the evaluation of the accumulation of Cd, Pb and Zn in five cultivars of Cichorium intybus L. (chicory) which were produced on contaminated agricultural soil. Over a growth period of 211 days, the roots and leaves were collected in four stages and then analyzed by flame atomic absorption spectrometry to measure the concentration and distribution of the target metals in these two chicory organs considering the weather and the nature of the cultivar. For all cultivars, sharp decreases of Pb (from 165 mg kg−1 to 3 mg kg−1), Cd (from 11 mg kg−1 to 5 mg kg−1) and Zn concentrations (from 157 mg kg−1 to 40 mg kg−1) in the roots were highlighted over time. The data collected enabled the calculation of the variation of the bioconcentration factor, the biological absorption coefficient and the translocation factor for Cd, Pb and Zn. These parameters were then correlated with the distribution of the fresh biomass of leaves and roots and several indicators such as chlorophyll content, flavonols, anthocyanin and nitrogen balance index were measured. The study concludes with the discussion on the ability of chicory to clean up contaminated agricultural soil. The current investigation has shown: i) a translocation of Cd (and Zn to a lesser extent) from the roots to the leaves; ii) an increase in the level of anthocyanins with the increase of the metal trace elements concentration in the leaf, while the content of chlorophyll and the nitrogen balance index decrease, which could be linked to the phenomenon of senescence; iii) an ability of the chicory to reduce the bioavailable pool of the three metal trace elements studied, in particular for Cd.