Changes in Some Antioxidant Enzyme Activities in Six Soybean Cultivars in Response to Long-term Salinity at Two Different Temperatures

In the present study, the effect of long-term salt stress (NaCl with 0, 0.1, 0.4 and 0.7 MPa)-temperature (25±2 oC and 35±2 oC) interaction on some antioxidant enzyme activities (ascorbate peroxidase, glutathione reductase and peroxidase) in six soybean cultivars (Glycine max L. Merr.) was investigated. The leaves of twenty-three-day old plants were used for the analysis of enzyme activities. Salt stress significantly increased APX activities of Mitchell, Nazlıcan and Türksoy compared to control, and decreased in other three cultivars at 25 oC, whereas it caused differences in the APX activities depending on the salt treatment levels at 35 oC. Under both temperatures, GR activities in the cultivars were generally increased by salt treatment, except for 0.1 MPa. POD activities at 25 oC decreased in all cultivars, except for 0.7 MPa in CX-415 and Nazlıcan. However, 0.4 MPa increased the activity only in cv. Nazlıcan at 35 oC. Our results demonstrated that the studied cultivars exhibited discrepancies in their antioxidant enzyme activities in response to salt treatment and the interaction of salt-temperature intensified the obtained responses.