Effect of salinity on some growth parameters in three Onobrychis species (Fabaceae) in Iran

Onobrychis is one of the important forage legume, which most of its wild species grow in Iran. In order to study of the effect of different salinity levels on percentage and rate of seed germination and also fresh and dry weights of seedlings in 3 Onobrychis species (O. subnitens, O. viciifolia and O. melanotricha), an experiment was carried out in three replicates using a factorial design with 5 treatments including 0 (control), 50, 100, 200 and 400 Mm NaCl. Results showed that as salinity increased, germination rate decreased in all species and was completely stopped in 400 mM NaCl. Results from mean comparison of fresh and dry weights of seedlings under salt stress showed that these parameters declined until 200 mM NaCl and there was a significant difference between different salinity levels. Results from guantitative and qualitative studies of proteins indicated that salt srtess decreased peroxidase and polyphenol oxidase activities, but increased total protein content. In addition, free proline content increased in response to salinity stress in the studied species, which was used for osmotic regulation.