Physiological and biochemical changes in sorghum under combined heavy metal stress: An adaptive defence against oxidative stress

In this study, the combined effects of five different heavy metals (HMs) (As, Ni, Cd, Pb and Cu) on sorghum (Sorghum bicolor (L.) Moench) seedlings were assessed with morpho-physiological and biochemical variations. Overall, the growth, total biomass and chlorophyll and relative water con tents in the leaves of the plants were de creased whereas electrolyte leak age was found to be increased in the higher con centrations (up to 500 mu M) of HMs. The up raised level of compatible soluble solutes such as pro line, mal on dialdehyde (MDA), glutathione (GSH), soluble proteins and higher accumulation of H2O2 were witnessed in HMs stressed plants. The HMs treated and con trol plants were examined for the level of anti-oxidative defense systems such as super oxide dismutase (SOD), catalase (CAT), glutathione reductase (GR). There was substantial collinearity be tween HMs concentrations and its physiological, biochemical and the antioxidant en zyme activities which can be used as biomarkers to observe HMs polluted sorghum plants. This study clearly deciphered the adaptive defense mechanisms of sorghum towards combined HMs induced toxicity.