Document Type : Original Article
In order to understand the response of tobacco to salt stress, antioxidant enzyme activities, plant biomass and ion content were analyzed in two oriental tobacco genotypes (Basma 31 and SPT 406). Tobacco plants were exposed to 0, 50, 100, 150 and 200 mM NaCl for 12 days. The fresh and dry weight as well as shoot and root length of Basma 31 were greater than those of SPT 406 under increasing salt stress. On exposure to NaCl, SPT 406 showed a higher Na/K ratio than that of Basma 31. Activity of catalase, ascorbate peroxidase and guaiacol peroxidase enzymes increased with increasing NaCl content in leaves of two genotypes, but activities of three enzymes in leaves of Basma 31 were higher than SPT 406. Activities of catalase and ascorbate peroxidase in roots of Basma 31 and SPT 406 increased with increasing external NaCl concentration up to 150 and 100 mM, respectively. The highest guaiacol peroxidase activity in roots of Basma 31 and SPT 406 was observed in 100 and 50 mM NaCl, respectively. These studies established that Basma 31 was able to tolerate higher salinity in comparison with SPT 406. Our results suggested that catalase, guaiacol peroxidase and ascorbate peroxidase play a major role in estimating the salt stress tolerance of tobacco genotypes.