Effect of Salinity Stress on Antioxidant Defense System of Niger (Guizotia Abyssinica Cass.)

Salinity is one of theprincipal abiotic stresses that affect plant productivity by inducing osmoticstress, which in turn, causes oxidative stress. Plants respond to thisoxidative stress by adjusting levels of antioxidants and associated components.10-day old seedlings of Niger were evaluated for abiotic stress response interms of antioxidants and antioxidant enzymes over 72 h in presence of up to500 mM NaCl in combination with CaCl2. Stress markers: H2O2,lipid peroxidation, antioxidants; ASC and GSH and antioxidant enzymes such asPOX, APX and GR were significantly elevated, while CAT was reduced. Theresponse was concentration and time-dependent up to 300 mM NaCl and fluctuatedbeyond. Metabolic enzymes β-amylaseand acid phosphatase exhibited moderate increase relative to controls. Theparameters indicated tolerance of the plants to salinity up to 300 mM over 48h