effect of different levels of salinity and nitrogen sources on growth and chemical contents in psyllium (plantago ovata f.)

in order to evaluate the effect of different levels of salinity and three nitrogen nutrition on biochemical reactions and changes in dry weight of shoot and root on psyllium (plantago ovata f.), a glasshouse experiment in a complete randomized design with three replications in 2009 at university of zabol was conducted. salinity treatments in this experiment were 0, 100 and 200 mm of nacl and nitrogen sources were nitrate, ammonium and nitrate+ammonium. planting was conducted in pots containing washed sand. salt stress in plants was started after two leaves stage and continued for 30 days. results showed that salinity, nitrogen sources and their interaction had significant effects on the dry weight in root and shoot of psyllium. salinity reduced dry weight of shoot and root. at 200 mm of nacl the dry weight of shoot and root reduced by 42.8 and 13.4%, respectively. at the highest level of salinity, ammonium+nitrate had the highest effect on root growth and shoot dry weight. in this study, salinity, nitrogen and their interaction (except nitrogen percentage) had significant effect on the values of nitrogen, nitrate, soluble protein and amino acids. salinity stress decreased all latter treatments. at the highest level of salinity, ammonium+nitrate nitrogen source increased them. by increasing salinity from control to 200 mm nacl, leaf chlorophyll content decreased but soluble carbohydrate and proline increased. nitrogen source treatment had only significant effect on proline. among the nitrogen sources, ammonium+nitrate had the highest effect on proline. use of nitrogen as ammonium+ nitrate at the highest level of salinity (200 mm nacl) improved the performance parameters of this plant.