Effect of Nitrogen and Silicon on Some Physiological Properties of the Pistachio Seedlings in Saline Conditions

In order to investigate the effect of nitrogen and silicon on some physiological Properties of the pistachio seedlings (Pistacia vera L. cv. Badami Zarand) in saline conditions, a factorial experiment was carried out in a completely randomized design with three replications under greenhouse conditions. Treatments consisted of nitrogen (0, 60 and 120 mg N kg-1 soil as NH4NO3), silicon (0, 1 and 2 mM as H4SiO4) and salinity (0, 1500 and 3000 mg NaCl and CaCl2 kg-1 soil with the ratio of two to one respectively) that at the end of the experiment created average salinity of 0.3, 9.7 and 20.9 dSm-1, respectively.Results showed that the salinity stress decreased the leaf relative water content and increased the electrolyte leakage, but application of 2 mM silicon increased the leaf relative water content by 28 percent and decreased the electrolyte leakage. Also combined application of 60 mg N kg-1 soil and 2 mM silicon increased the concentration of proline 36 percent compared to the control. The highest amount of soluble sugars in saline conditions was achieved with the application of 2 mM Silicon that increased more than 2 folds compared to the control. Although salinity stress decreased the shoot Fe, Mn and Zn concentrations significantiy, but application of the nitrogen and silicon increased the concentration of these elements significantiy. According to the results of this experiment, it is concluded that the combined application of nitrogen and silicon in saline conditions through improving the physiological Properties increased the ability of pistachio seedlings in tolerance to salinity stress.