Effect of Nitrogen on Physiological Characteristics and Macronutrients Concentration of Three Olive (Olea europaea L.) Cultivars under Salt Stress

In this research the interaction effects of NaCl and nitrogen concentrations, on some physiological, biochemical, and growth characteristics of three olive (Olea europaea L.) cultivars (Abou-Satal, Arbequina and Conservolia) were investigated. The experiment was conducted as factorial with four NaCl levels (0, 40, 80, and 160 mM) along with three (NH4)2SO4  levels (0, 200, and 400 mg L-1) based on a completely randomized blocks design with three replications. Salinity had a statistically significant negative effect on responses considered, although the severity of the effect varied among cultivars. High concentration of salinity decreased the plant height, leaf number, root and leaf K/Na ratio, N absorption and concentration of root and leaf, K, Ca, Mg and P both of root and leaf while increased the root and leaf Na and Cl concentration. Increasing N levels to 200 mg L-1 has improved the plant height and leaf number. At 200 mg L-1 N concentration, Na, Cl and Ca root and leaf were decreased whereas, K/Na ratio, N absorption and concentration also K, Mg and P of root and leaf were increased. It can be concluded that under salinity condition increasing N concentration up to 200 mg L-1 in salt sensitive cultivars to salinity is favorite in counteracting the adverse effects of salinity but the further increase of N concentration (400 mg L-1) may be ineffective or harmful for the growth of olive plants. In this experiment, investigation cultivars responses to salinity showed that cv. Abou-Satal is a highly resistant at highest salinity level (160 mg L-1), also cv. Arbequina is semi-sensitive and cv. Conservolia is a sensitive to salinity condition.