effects of salinity on ion exchanges in halocnemum strobilaceum and halostachys caspica

salinity is one of the most brutal environmental stresses that hamper crop productivity worldwide approximately 10% of the total land surface is salt affected and about 10 million hectare of agricultural land is lost annually due to salinization and water logging. this study was conducted to determine the ion exchanges in halocnemum strobilaceum and halostachys caspica in saline conditions. the seeds of plants were sown in the pots in a greenhouse in research institute of forests and rangelands, iran. after 5 months, plants were exposed to different salinity levels including 0, 100, 200, 300, 400 and 500 mm of nacl and na2so4 for 45 days and the amounts of na+, k+, mg2+ and ca2+ were measured in stems and roots. results showed that ion contents were affected by nacl and na2so4 in both species. the minimum and maximum values of na+ (568 and 1613mg kg-1 dm) were found in the root of h. caspica and shoot of h. strobilaceum, respectively. ion content was increased with the increase of salinity up to 100 and 200-300 mm in h. strobilaceum and h. caspica, respectively.also, the ion exchanges were higher in h. strobilaceum than h. caspica. in general, this investigation showed the ion uptake of both species at low salinity but they changed the tolerance mechanism at high salinity. so, na+ and k+ were translocated from shoot to root while ca2+ translocation from root to shoot was increased by salinity.