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In Argentina cultivated grasses are the livelihood of the traditional livestock systems. Actually, the introduction of pastures in arid zones is one of the major challenges for ranchers. The aim of this work was to assess the germination of four forage species: Agropyron elongatum, Antephora pubescens, Cenchrus ciliaris cv Texas and Panicum coloratum cv Klein verde under water stress and salinity. Were used solutions of NaCl, KCl, Na2SO4, K2SO4 and Mannitol as inert solute, obtaining osmotic potentials (Psi o) of -0.5, -1, -1.5 -2.0, or -2.5 MPa. Seeds were cultivated in Petri dishes on germination paper, watered with 4 mL of deionized water and incubated to 25 degrees C. We used a completely randomized design with 4 repetitions. During 10 days, the number of sprouted seeds was counted daily, and the percentage of germination, the speed of germination (ERI) and the mean time to germination (MTG), were calculated. Data were analyzed with the statistical software Infostat. Germination declined with increasing concentration of the solution in the four species. In general, salts of SO4-(2) proved more damaging to the germination than those of Cl-. Cenchrus ciliaris cv Texas was the most water stress tolerant species, with percentages of germination close to 50% even in To of -2.5 MPa. On the contrary, Panicum coloratum cv Klein verde was the less tolerant, with low percentages of germination at -1 MPa, and no response to Psi o of -1.5 MPa or lower.