Abstract: Cadmium (Cd) is a non-essential heavy metal that does not have any metabolic
use and can be harmful even at low concentrations. Blackgram (Vigna
mungo L. Hepper cv. T9) plants were grown in pots containing a mixture
of soil and compost treated with 0, 25, 50 and 100 mg Cd kg-1
soil as CdCl2 for 30 days. The changes in total Chlorophyll
(Chl), Chl a/b, net photosynthetic rate (PN), stomatal conductance
(gs), Water Use Efficiency (WUE) and Carbonic Anhydrase (CA) activity
were noted. The activities of antioxidative enzymes in root and leaf were
also assayed together with the content of Thiobarbituric Acid Reactive
Substances (TBARS) and hydrogen peroxide (H2O2).
The concentration of Cd in root and leaf increased with the increasing
Cd concentrations. Greatest decrease in photosynthetic traits was observed
with 100 mg Cd kg-1 soil. The activity of Superoxide Dismutase
(SOD) increased in leaf but decreased in root, whereas the activity of
catalase (CAT) decreased in both root and leaf. By contrast to CAT, the
activity of ascorbate peroxidase (APX) increased in root and leaf. However,
GR activity increased in root and decreased in leaf. The results suggest
that the antioxidative enzymes showed differential pattern in root and
leaf and the decrease in photosynthesis with 100 mg Cd kg-1
soil was associated with the accumulation of TBARS and H2O2
content and reduction in Chl content, stomatal conductance and CA activity. |