Modulation of oxidative damage due to salt stress using salicylic acid in Hordeum vulgare

Oxidative status of salicylic acid (SA) treated barley (Hordeum vulgare) plants grown under saline conditions was examined in a two-year field study during 2012–2013 and 2013–2014 growing seasons. Salinity caused a marked oxidative stress which was manifested as increased concentration of hydrogen peroxide (H₂O₂) and reduced grain yield of barley. Barley plants induced antioxidant system to tolerate salt stress, so that activities of four antioxidant enzymes: peroxidase, catalase, superoxide dismutase and glutathione reductase were enhanced by 22%, 28%, 57% and 44% in the first and by 33%, 20%, 45% and 68% in the second year, respectively. Foliar application of SA in concentration over 0.5 mM enhanced the activities of all four antioxidant enzymes and reduced H₂O₂ content and so enhanced yield. However, higher concentrations of SA reduced grain yield in salt stressed plants in both years, which could be attributed to the negative interaction of antioxidant enzymes with higher concentrations of SA as a non-enzymatic antioxidant. Furthermore, SA is in benzoic acid group and at very higher concentrations can act as an herbicide. It was concluded that SA modulated the oxidative stress through enhanced activities of antioxidant enzymes and reduced the salt-induced adverse effect thereby improving grain yield.