Abstract
The study was conducted at a greenhouse of the Graduate School of Biosphere Science in Hiroshima University, Japan under the ambient conditions to find out the effect of salinity stress on some physiological and biochemical characteristics of two bread wheat genotypes and also to elucidate the salt tolerance mechanism of these wheat genotypes. Two wheat genotypes namely 'Sakha 95' and 'Misr 2' were exposed to 50, 100 and 150 mM NaCl levels of salinity Results showed that both genotypes were varied significantly for all traits under all levels of salt stress. Among the genotypes, growth of the genotype 'Misr 2' was found much better than the 'Sakha 95', with the maintaining a higher dry biomass. The genotype 'Misr 2' also maintained a high concentrations of soluble-sugars, proline, and various antioxidant enzymes activity such as glutathione reductase (GR), peroxidase (POD) and catalase (CAT) compared with genotype 'Sakha 95'; whereas, maintained a lower levels of lipid peroxidation represented by the malondialdehyde (MDA) concentration. Indicating that genotype 'Misr 2' has ability to survive under salinity stress than the genotype 'Sakha 95'. Similarly, salinity stress also significantly changed in Ca++ contents and Na+/Ca++ ratio in both wheat genotypes. The relative reduction in Ca++ concentration and Na+/Ca++ ratio was found higher in the genotype Sakha 95' than in 'Misr 2' and lead to showing the signs injury. Thus, the genotype 'Misr 2' would be useful to develop a salinity tolerant wheat varieties in the future breeding program.