How Does Salinity Duration Affect Growth and Productivity of Cultivated Barley?

Little is known about the ability of cultivated barley (Hordeum vulgare L.) to recover from salt stress. In a pot experiment, barley plants (cultivar Lamsi) were treated with up to 200 m M NaCl for 0, 15, 30, 45 or 60 d. Plants were collected at the end of each of these salt-treatment periods and at grain maturity. Plant growth, leaf organic and inorganic solutes, and sonic physiological and productivity parameters were determined. Salinity reduced fresh and dry weight, relative growth rate (KGR), leaf water potential, and osmotic potential at full turgor whereas it increased leaf Na+ and Cl- concentration and tissue rigidity. However, the adverse effect of salinity on plant growth was observed relatively late (after 15 d of salt treatment), suggesting that during the first period of treatment, the effect of salinity is osmotic rather than salt specific. Grain number per plant, and grain productivity (g plant(-1)) were more responsive to salinity than other assessed parameters. After stress removal, only seedling treated with up to 200 mM NaCl for 15 d could completely recover, whereas plants exposed to salinity for 30 d or longer were not able to recover. As a whole, osmotic adjustment and cell wall elasticity (CWE) represent important components for barley adaptation to salinity in a 15-d time frame. However, they are not sufficient to provide increased barley salt tolerance under prolonged period of treatments.