Distribution of Bio-accumulated Cd and Cr in two Vign species and the Associated Histological Variations

In nutrient culture experiments, bioaccumulation and anatomical effects of cadmium (CdCl2 - 20μM) and chromium (K2Cr2O7 - 600 μM) on the structure of root and stem was studied by histochemical and analytical methods in Vigna radiata and Vigna unguiculata. Each metal exerted specific influences on the anatomy of various tissues in root and stem. Histochemical localisation of cadmium and chromium was observed in the stained sections of root and stem. Atomic Absorption Spectrophotometric study revealed maximum accumulation of cadmium and chromium in the root tissue as compared to shoot with significant variation among the species. Abundant occurrences of densely stained deposits of chromium were seen in the root stelar region of V. unguiculata and to a lesser extend in V. radiata. Cadmium accumulation in V. radiata was comparatively more than that of V. unguiculata. The findings also revealed that the accumulation pattern of cadmium and chromium varies between species and hence is species specific.