PTE transfer from polluted soils to crop plants is a process of great
importance, because it is considered as one of the major pathways of
human exposure to soil pollution (Khan et al., 2008; Liu et al., 2013).
Moreover, plant growth can be adversely affected by PTEs due to their
influence on biochemical processes such as metabolism, respiration,
photosynthesis and stomata opening (Smical et al., 2008). The accumulation
of high levels of metals in crop tissues depends on the plant species,
and the efficiency of different plants in absorbing PTEs is assessed
by either plant uptake or soil-to-plant transfer factors (Rattan et al.,
2005). According to Kachenko and Singh (2006), metal transfer factors
(TF) may quantify the existing differences in the bioavailability of
metals to plants, indicating their mobility in the soil.