Effect of Salinity Stress on Antioxidant Defense System of Niger (<i>Guizotia abyssinica</i> Cass.)

Abstract

Salinity is one of the principal abiotic stresses that affect plant productivity by inducing osmotic stress, which in turn, causes oxidative stress. Plants respond to this oxidative stress by adjusting levels of antioxidants and associated components. 10-day old seedlings of Niger were evaluated for abiotic stress response in terms of antioxidants and antioxidant enzymes over 72 h in presence of up to 500 mM NaCl in combination with CaCl 2 . Stress markers: H 2 O 2 , lipid peroxidation, antioxidants; ASC and GSH and antioxidant enzymes such as POX, APX and GR were significantly elevated, while CAT was reduced. The response was concentration and time-dependent up to 300 mM NaCl and fluctuated beyond. Metabolic enzymes β -amylase and acid phosphatase exhibited moderate increase relative to controls. The parameters indicated tolerance of the plants to salinity up to 300 mM over 48 h.