Effects of Nitrogen Nutrition and Salinity Stress on 1000-Grain Weight, Mucilage Content and Nutrient Uptake in Psyllium (Plantago ovata F.)

In order to investigate the effects of salinity stress and three nitrogen fertilizers on some traits of psyllium (Plantago ovata) plants, a factorial experiment, as completely randomized design with three replications, was carried out at University of Zabol, in 2010. Salinity at three levels (0, 100 and 200 mM sodium chloride) was the main plot and three forms of nitrogen source (nitrate from calcium nitrate, ammonium from ammonium sulfate, and ammonium + nitrate (50: 50)) were the sub-plot. Seeds were sown in pots containing clean sand. After germination, plants nutrition was by application of Hoagland solution, which was prepared according to the nitrogen treatments. Salinity stress was started at 2-leaf stage. Results showed that salinity significantly affected 1000-grain weight, spike length, mucilage content of grains, and swelling index of psyllium grains. By increasing salinity level, the spike length and 1000-grain weight were decreased 21.5% and 27.3%, respectively. Among the four mentioned traits, interaction of salinity and nitrogen treatment significantly affected only the spike length. Maximum spike length was obtained in non-saline treatment and ammonium fertilizer. Salinity stress increased the sodium and chlorine ions and decreased the potassium content in shoots. Nitrogen source and interaction between salinity and nitrogen significantly affected the content of these elements in plants. The highest concentration of sodium and potassium was obtained in 200 mM sodium chloride and non-saline treatments (control), respectively, along with application of ammonium fertilizer.