Differences in physiological traits among salt-stressed barley genotypes

The effect of salinity on some physiological parameters in 16 barley genotypes with different salt tolerance was investigated. The results showed 50 mM NaCl treatment increased Na+/K+ ratio, malondialdehyde (MDA) and proline contents, and decreased cell membrane stability index (CMSI) and fresh shoot biomass (FSB) of all tested genotypes. Salt stress also resulted in a decreased chlorophyll (Chl) content and net photosynthesis (Pn) for most genotypes. Under higher salt stress (300 mM NaCl), the marked increase for Na+/K+ , MDA, and proline content, and decrease for other parameters were found for all genotypes. The affected extent of these parameters by salt stress varied with genotypes. Proline accumulation in barley was associated with injured extent under salt stress, indicating it is not a defensive reaction to the stress. K+ uptake was less affected, whereas Na+ accumulation in plants was enhanced under high salt stress. The correlation analysis showed that MDA and proline content, Na+ concentration and Na+/K+ were negatively correlated with FSB, whereas other parameters examined in the study were positively correlated with FSB.