2Department of Plant Science, Technische Universität München, Emil-Rahmann-Str. 2, D-85350 Freising-Weihenstephan, Germany.
3Division of Crop Production and Environment, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan).
Parameters that show a significant genotypic variation at early growth stages and are associated with salt tolerance at later stages may be used as rapid and economic screening criteria in breeding programs. The objective of this study was to test growth parameters at early growth stages for evaluating the salt tolerance of wheat genotypes. Ten wheat genotypes that differ from their salt tolerance were grown in soil and exposed to four salinity concentrations (0, 40, 80 and 160 mM NaCl). Germination percentage was recorded daily up to 8 days. Seedling growth parameters (i.e. shoot height, dry weight of shoots and roots and root/shoot ratio) were determined at day 14 after sowing. The results showed that salinity did not affect final germination percentage, while seeds subjected to 80 and 160 mM NaCl retarded germination by 1 and 2 days, respectively, as compared with 0 mM NaCl treatment. Salinity affected shoot growth more severely than root growth of seedlings. Importantly, height and dry weight of shoot ranked genotypes in the same order as their salt-tolerance rankings in terms of grain yield, whereas root dry weight did not. Therefore, we conclude that the measurements of shoot growth may be effective criteria for screening wheat genotypes for salt tolerance at early growth stages.