Effects of Sequential Hydrogen Peroxide Applications on Salt Stress Tolerance in Bread Wheat Varieties

Abstract

Salinity is affecting plant growth and development. Low concentration of hydrogen peroxide (H2O2) has shown to be effective against various stress factors. In this study, effect of different H2O2 priming methods on growth, physiological and biochemical parameters in three wheat varieties (NKU Lider, Sultan-95, and Tosunbey) under salt stress were investigated. Salt stress (0 and 160 mM NaCl) was applied gradually to 100 mu M H2O2 applied (-H2O2: negative control, no application; H2O2: positive control, 100 mu M H2O2 applied; 1xH2O2: 100 mu M H2O2 applied one year ago; 2xH2O2: 100 mu M H2O2 applied second time after one year) wheat seedlings. Biochemical results showed that the lowest H2O2 level was in NKU Lider variety and in-H2O2 and 1xH2O2 groups. The lowest thiobarbituric acid reactive substances (TBARS) level was in Tosunbey variety and 2xH2O2 group. The highest superoxide dismutase (SOD) activity was in NKU Lider variety, all H2O2 pre-treatment caused an increase in SOD activity and 2xH2O2 pre-treatment caused the highest SOD activity. However, H2O2 and TBARS levels increased in all application groups except 2xH2O2 group, while the H2O2 amount increased and TBARS level decreased in 2xH2O2 group. MnSOD was not detected in any groups. CuZnSOD increased in all groups except 2xH2O2 groups under salt stress in Sultan-95 variety compared to FeSOD. H2O2 pre-treatment better tolerated salt stress, and second-applied H2O2 pre-treatment eliminated the stress and improved plant growth. In conclusion, it was determined that H2O2 re-pre-treatment to wheat seeds resulted in improvement of plant growth in tolerant varieties exposed to salt stress.