Abstract

This study was conducted to determine physiological respons of Lolium perenne L. ‘Bartwingo’ and Poa pratensis L. ‘Barimpala’ to salinity and ammonium: nitrate ratio during germination and early seedling growth. The five salinity levels (0, 20, 40, 60 and 80 mili molar sodium chloride) were applied in half strength Coic nutrient solution containing 6 meq l^-1 nitrate and 4 ammonium levels (0, 0.25, 0.5 and 1 meq l^-1). In general Salinity reduced germination percentage and rate, shoot and root length and shoot chlorophyll content in both species. Shoot proline and malondialdehyde content increased as salinity levels increased. Regardless of salinity, effects of ammonium levels were not considerable, but interaction between salinity and ammonium concentrations showed that in both species, at higher salt concentrations, increasing ammonium concentrations reduced germination rate, shoot and root length and shoot chlorophyll and increased proline and malondialdehyde, whereas in nonsaline nutrient solution or in low salinity levels there was no significant difference amomg ammonium levels and in some parameters result was opposite with those in higher salinity. These data suggest that, feeding these two turfgrass cultivars with mixture of nitrate and ammonium (according to Coic nutrient solution) results the best growth, but in high salinity medium, ammonium levels must be reduced as salinity increases.