Effects of magnetic fields on some physiological factors and antioxidant capacity of Silibum marianum L. seedlings under salt stress

Salinity is one of the most important abiotic stresses that have restricted affects on plant growth and yield. Magnetic field can ameliorate the negative effect of salinity with induction of plant antioxidant activity. In present research, the effect of static magnetic fields (0 anf 4 mT) on some physiological parameters and antioxidative capacity were investigated under salinity stress at concentrations of 0, 50 and 100 mM NaCl in Silibum marianum L. The results showed that salinity at 100 mM and no a magnetic field pretreatment led to reduction in fresh (65%) and dry weight (27.7%), relative water content (15.35%), leaf area (29.82%), root length (8.30%) as comparied to control. The lowest IC50 (22.32%) was observed at 50 mM salinity and a magnetic -field strength of 4 milli- tesla . Proline, MDA, hydrogen peroxide, total phenol and flavonoid contents were also significantly increased under 100 mM NaCl treatments. The magnetic field reduced the negative effects of salinity on growth indicators of S. marianum seedlings by increasing the antioxidant capacity, proline, the total phenolic and  flavonoid contents. 4 mT magnetic field also led to a 28.3 and 35.4% reduction of hydrogen peroxide and MDA levels under 100 mM NaCl concentrations. It seems that magnetic field pre-treatment can be reduced the adverse effects of salt on this plant species by increasing antioxidant capacity especially at 50 mM.