The effects of salinity on antioxidant enzymes activity in the leaves of two contrast rice (Oryza sativa L.) cultivars

Abstract

The aim of this research was to assess the effects of salt stress on antioxidant enzymes activity in rice leaves. Experiment design was completely randomized design in a factorial arrangement with two genotypes (improved cultivar of Ghaem and traditional cultivar of Sangejo) and four salinity levels (0, 40, 80 and 120 mM NaCl) with three replicates. Salt stress treatments were initiated at 16 days after planting, and then activities of some antioxidant enzymes such as catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) were determined. Results of variance analysis showed that the interaction of salinity and the cultivar for CAT, POD, APX (α= 0.01) and SOD (α= 0.05) were statistically significant. Activity of all studied enzymes in Sangejo cultivar increased with increasing the salt stress treatments whereas in Ghaem cultivar, CAT and SOD activities had no clear trend. Results of regression analysis for antioxidant enzymes in Sangejo cultivar showed a significant correlation between antioxidant enzymes and salt stress levels. By contrast, in Ghaem cultivar there was a weak relationship between both CAT and POD (R2=0.21) and APX (R2=0.33) activities. In conclusion, the results of the current study indicated that Sangejo cultivar was more tolerant to salt stress as compared to newly released cultivar of Ghaem.