Salinity Induced Changes in Oxidative Stress and Antioxidant Status as Affected by Applications of Silicon in Lettuce (Lactuca sativa)

Abstract

The antioxidant content, capacity and certain oxidative stress parameters were investigated in salinity stressed Lactuca sativa L. ‘Eish!’ with the addition of exogenous silicon (Si). No significant changes were shown for total polyphenol concentrations in any of the experimental plants. Applications of 4 mM Si significantly increased oxygen radical absorbance capacity analysis (ORAC) values at both 30 and 60 mM NaCl. The redox status of glutathione was also improved with a significant increase in reduced glutathione (GSH) in 2 mM Si treated plants at 30 mM NaCl. Increases in both GSH and oxidised glutathione (GSSG) were noted at 60 mM NaCl. The activity of catalase (CAT) was significantly decreased with the addition of 1 and 4 mM Si at 30 mM NaCl. Lipid peroxidation (measured as thiobarbituric acid reactive substances, TBARS) was not influenced by the different Si concentrations. These results suggest that applications of Si could be beneficial with regards to the modulation of oxidative stress in salinity stressed lettuce and should be considered as an addition when cultivating lettuce.