Effect of salinity on growth, ion content and water status of glasswort (Salicornia herbacea L.)

Salinity is one of the major environmental stresses that limit plant growth and productivity. Glasswort (Salicornia herbacea L.) is one of the native halophytic plants of Iran that widely spread in salt areas. The purpose of this study was to determine the physiological and growth responses of S. herbacea to salinity stress. Plastic pods (15 cm diameter, 20 cm height) with the Silica sand bed were used for the experiment. The solution used for the study consisted of 0 (control), 100, 200, 300, 400, 500 mM of NaCl and Na2SO4. S .herbacea seeds cultivated at five pots for each treatment in green house condition. Plants were irrigated with half strength Hoagland?s nutrient solution for 6 months. Salt treatments were applied for 45 days. Shoot and root dry weights, proline, glucose, ion concentration, Osmotic Potential (OP), Relative Water Capacity (RWC), Water Use Efficiency (WUE) ?Net Assimilation Rate (NAR), Specific Leaf Area (SLA) and Leaf Area Ratio (LAR) were measured. Data analysis showed that Mg 2+, Ca+2 and K+ decreased when salinity increased but Na+ increased. CL- increased when NaCl increased but significantly inhibited at higher Na2SO4. Dry weight, WUE, SLA, NAR and LAR increased in up to 100 to 300 mM NaCl and Na2SO4 but decreased with a further increase in salinity. S. herbacea uptakes more ions in chloride soil than that of sulfate soil. WUE, NAR and dry weight are more at sulfate soil. It is also assumed that salt tolerance mechanism of S. herbacea changes at different salts. Measurement of osmotic potential showed that it did not significantly increased when salinity increased. In addition, glucose did not promote up to 400 mM. Therefore, S. herbacea L. is a high tolerant halophyte which grows well up to 500 mM of NaCl and Na2SO4 salt. Salinity enhances the growth of S. herbacea and its optimum growth occurs at 100 ? 300 mM. Proline, glucose and osmotic potential remain unchanged at moderate salt concentrations. Also, it tolerates salinity via uptake of ions at NaCl and also ions repulsing and increasing WUE at Na2SO4. S. herbacea grows at sulfate better than chloride.