Effect of different zinc levels on some physiological characteristics of Plantago ovata under salt stress

The use of micronutrient fertilizers, such as zinc on the condition of natural limiting factors such as salinity can be a great help in the development of medicinal plants cultivated in many parts of the country. In order to study the response of Plantago ovata to zinc application under salt stress, a pot experiment was conducted in 2013, as factorial experiment based on a complete randomized design with four replications. Treatments were five levels of salinity (0, 50, 100, 150 and 200 mM NaCl) and three levels of zinc (3.85, 7.7 and 11.55 µM ZnSO4). The interaction effects of salinity and zinc on physiological parameters of Plantago ovata were significant. With increasing concentration of zinc at zero, 100 and 150 mM salinity, leaf soluble sugar increased 50%. At zero and 200 mM salinity, with increase zinc concentrations levels of proline were increased over two times. Salinity increased the percentage of electrolyte leakage, so that by increasing the salinity level, leakage rate increased from 30 to 50%. Leaf soluble protein with increasing amounts of zinc, increased 36%. Generally use of 7.7 µM zinc in all of traits associated with a better outcome, and also, if consumed a large amounts of zinc in a high salt concentrations, the amount of compatible solutes (leaf soluble sugars and proline) increased. Therefore, to reduce the effect of salinity can be used zinc concentration in Hoagland solution up to 7.7 µM