Comparative salt tolerance of two wild Hordeum species (H-maritimum With. and H-murinum L.) from the coast of Tuscany (Italy)

The differences in salt tolerance between Hordeum maritimum and H. murinum were studied. Seeds were collected at horn maturity from wild populations g rowing respectively near the Orbetello Lagoon and S. Piero a Grade (Tuscany , Italy) and were used in germination and growth tests at increasing salini ty (NaCl) levels. H. maritimum was confirmed to be a true halophyte as comp ared to H. Murinum, which exhibited germination behavior typical of many wi rd glycophytes. The higher salt sensitivity of H. murinum compared to H. ma ritimum was also shown by its shoot length values, which decreased only in H. murinum, albeit in 100 mM NaCl treatment. The higher degree of salt tole rance of H. maritimum is further demonstrated by the Na : K ratio. H. marit imum can accumulate a greater amount of sodium than potassium in both roots and shoots, even in the absence of salt treatment. However, in NaCl soluti ons H. maritimum showed a higher Na : K ratio for shoots - an index of bett er uptake and translocation of sodium to leaves - as has been for many halo phyte includers. These results thus help to enhance knowledge on wild relat ives of barley, whose potential contribution to genetic improvement in sali nity tolerance has previously not been thoroughly explored.