Photosynthesis capacity and enzymatic defense system as bioindicators of salt tolerance in triticale genotypes

• Photosynthetic capacity in triticale did not contribute to salt tolerance in all growth stages.
• Antioxidant enzymes activities were stage specific and were not indicator of tolerance.
• Lipid peroxidation was a reliable biomarker for salinity tolerance.

The present study aims at clarifying the differences in photosynthesis parameters, oxidative status and antioxidant enzyme activity among ten triticale genotypes in response to salinity stress; and utilizing the traits as biomarkers for identification of salt-tolerant triticale genotypes. The plants were cultivated in a hydroponic system with or without 220 mM salt concentration. The plants were analyzed for salt tolerance (in term of relative biomass) as well as for the traits at the vegetative (VG) and reproductive (RP) stages. Salinity resulted in significant decline in biomass (55–83%), net photosynthesis rate (12–65%), stomatal conductance (38–83%), transpiration rate (20–56%) and intercellular CO2 concentrations (7–37%) among genotypes. In contrast, H2O2 and lipid peroxidation (LP) increased markedly in leaves of salt-stressed plants. Activities of total superoxide dismutase (TSOD), catalase (CAT), guaiacol peroxidase and ascorbate peroxidase due to salinity were 0.97–1.84, 0.88–1.96, 0.78–2.23 and 0.61–1.81 times over the control plant, respectively. The photosynthesis attributes, LP and TSOD at the VG stage and LP and CAT at the RP stage showed correlations with scores of salt tolerance (ST) indicating contribution of these traits to ST at least at some part of the plant growth stages, while no connection was found between ST with POD and CAT. Collectively, membrane integrity was a suitable indicator for discrimination of genotypes for ST, while photosynthetic capacity and enzymatic defense system cannot be utilized as general selection criteria for ST during screening of relatively large populations of triticale.