RESPONSE OF LEAVES, STEMS AND ROOTS OF WITHANIA SOMNIFERA TO COPPER STRESS

Abstract

The effects of Cu+2 stress (0, 10, 20, 50, 100 and 200 mM as CuSO4.5H2O) on growth and biochemical parameters of Withania somnifera L.Dunal, grown in a field pot experiment were studied. Increasing Cu+2 concentrations led to decreased stem length, root elongation and leaf area. Copper (Cu+2 ) stress decreased chlorophyll and carotenoids content in leaves and stems as compared to controls; this was more pronounced in leaves than in stems. Lipid peroxidation, in terms of malondialdehyde (MDA) content increased. Lipid peroxidation increased significantly with elevation in Cu+2 concentrations and was highest in roots followed by leaves and stems at 200 mM. Leakage of electrolytes measured in terms of membrane stability index (MSI), which showed a negative correlation with increasing Cu+2 levels. The MSI was lowest in 200 mM Cu+2 treated plants. The phenol content of leaves, stems and roots peaked at 50 mM Cu+2 treatment and thereafter declined. These results indicate that Cu+ 2 stress negatively impacted nearly all the parameters assayed; particularly in the roots. It is being reported for the first time that stress resistance in W.somnifera as observed by increase in total phenol content at low Cu+2 levels possibly to combat increased ROS generation.