SALINITY TOLERANCE IN BARLEY (HORDEUM VULGARE L.): EFFECTS OF VARYING NaCl, K+/Na+ AND NaHCO3 LEVELS ON CULTIVARS DIFFERING IN TOLERANCE

Although barley (Hordeum vulgare L.) is regarded as salt tolerant among crop plants, its growth and plant development is severely affected by ionic and osmotic stresses in salt-affected soils. To elucidate the tolerance mechanism, growth and ion uptake of three barley cultivars, differing in salt tolerance, were examined under different levels of NaCl, K+/Na+ and NaHCO3 in the root medium. The cultivars differed greatly in their responses to varying root medium conditions. Plant growth was more adversely affected by NaHCO3 than NaCl. In general, biomass yields were comparable under control and 100 mM NaCl. However, growth of all three cultivars was significantly inhibited by NaHCO3 even at low concentration (10 mM). Improved K+ supply in saline medium increased K+ uptake and growth of less tolerant cultivars. K+ uptake was more adversely affected by NaHCO3 than NaCl salinity. Selective K+ uptake and lower Cl-in shoots seemed to be associated with the growth responses. K application would help better growth of these cultivars on K-deficient saline-sodic soils and under irrigation with poor quality water having high Residual Sodium Carbonate (RSC) and/or Sodium Adsorption Ratio (SAR).