The bioaccumulation efficiency of
cadmium (Cd) by fenugreek (Trigonella foenum-graecum) was examined using different concentrations of
CdCl2. The germination rate was similar to control except
at 10 mM Cd. However, early seedling growth was quite sensitive to the
metal from the lowest Cd level. Accordingly,
amylase activity was reduced substantially on treatment of seeds with 0.5, 1, and 10 mM Cd.
Cadmium also affected various other plant growth parameters. Its accumulation was markedly lower in shoots as compared to roots, reducing root biomass by almost 50 %. Plants treated with 1 and 5 mM Cd presented
chlorosis due to a significant reduction in
chlorophyll b especially. Furthermore, at Cd concentrations greater than 0.1 mM, plants showed several signs of oxidative stress; an enhancement in root
hydrogen peroxide (H2O2) level and in shoot
malondialdehyde (MDA) content was observed. Conversely,
antioxidant enzyme activities (
superoxide dismutase (SOD),
ascorbate peroxidase (APX), and
catalase (CAT)) increased in various plant parts. Likewise, total phenolic and
flavonoid contents reached their highest values in the 0.5 mM Cd treatment, consistent with their roles in quenching low concentrations of
reactive oxygen species (ROS). Consequently, maintaining
oxidant and
antioxidant balance may permit fenugreek to hyperaccumulate Cd and allow it to be employed in extremely Cd polluted
soils for detoxification purposes.