Contrasting leaf Na+ uptake and transport rates conferred differences in salt tolerance of wheat genotypes

The genotypic differences regarding Na+ accumulation and transport in plants along with the physiological response to improve salt tolerance were studied in bread wheat genotypes. Four wheat genotypes; Kharchia-65, SARC-3, S-9476, and S-8189 were grown under salt stress (75 and 150 mM NaCl) in nutrient solution with five replications. Shoot dry weight, relative growth rate (RGR), chlorophyll index, leaf water relations, Na+ content, and transport in plants were measured. The increase in NaCl stress decreased all growth parameters; however, variations were observed among genotypes. Kharchia-65, S-9476, and SARC-3 had better growth and water relations compared with the salt-sensitive genotype S-8189. The low rate of Na+ transport and better ability to restrict Na+ in the root was the main reason for genetic variation among different genotypes, especially when growth characteristics did not vary significantly under salt stress. Na+ partition was also recorded in the wheat genotypes, since salt-sensitive genotypes had higher Na+ accumulation in shoot while this was reversed in tolerant ones. The differences in root Na+ were not significant among all genotypes.