Salt Tolerance in the Triticeae: K/Na Discrimination in Barley

Concentrations of ions were measured in the youngest fully-expanded leaves of Triticum aestivum, T. durum, Hordeum vulgare, H. spontaneum, Secale cereale, and Aegilops squarrosa accessions grown in hydroponic culture in the presence of salt (NaCl+CaCl2). Triticum aestivum, Secale cereale, and Ae. squarrosa had the low leaf Na and high leaf K concentrations typical of plants which contain the enhanced K/Na discrimination character originally found in Ae. squarrosa. T. durum and the Hordeum species did not have this character. The better growth of H. vulgare than of T. durum with similar salt concentrations in the youngest fully-expanded leaves may be a result of better compartmentation of Na, Cl, and K between different tisssues or between different compartments within cells. The enhanced K/Na discrimination character was expressed in disomic addition lines of H. vulgare chromosomes in Triticum aestivum. The H. vulgare variety Herta and its slender mutant both had similar leaf cation concentrations, although they differed in growth rate when grown at 60 mol m−3 NaCl. H. vulgare and T. durum seedlings grown in the absence of monovalent cations accumulated more 22Na in their shoots than seedlings of other species when incubated in 1.0 mol m−3 NaCl labelled with 22Na.