PHYSIOLOGICAL AND BIOCHEMICAL ALTERATIONS IN ANDROGRAPHIS PANICULATA UNDER CADMIUM AND SODIUM STRESS

Abstract

Abiotic stresses such as heavy metal contamination and salinity severely affect the growth, physiology, and metabolic homeostasis of medicinal plants. The present study investigates the physiological and biochemical alterations in Andrographis paniculata under cadmium (Cd) and sodium (NaCl) stress. Uniform seedlings were subjected to varying concentrations of CdCl₂ and NaCl under controlled growth conditions. Physiological parameters including plant height, biomass accumulation, chlorophyll content, and relative water content were significantly reduced with increasing stress intensity. Both Cd and sodium stress induced excessive generation of reactive oxygen species, as evidenced by elevated levels of hydrogen peroxide and malondialdehyde, indicating enhanced lipid peroxidation. In response, antioxidant defence systems were markedly activated, with increased activities of superoxide dismutase, catalase, and peroxidase, although prolonged or higher stress levels caused partial enzyme inhibition. Biochemical analysis revealed a decline in total soluble protein and carbohydrate content, while stress-induced modulation of secondary metabolites, particularly andrographolide and total phenolics, was observed. Cadmium stress exerted more pronounced toxic effects compared to sodium stress, while combined responses highlighted the adaptive potential of A. paniculata through metabolic reprogramming and antioxidant regulation. The findings provide valuable insights into stress tolerance mechanisms in A. paniculata and have implications for its cultivation in metal- and salt-affected soils.