Document Type : Research Paper
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Abstract
The current research was conducted at Qom Fadak Greenhouse to study the effects of different salinity levels on physiologic and morphologic characteristics of three rangeland species (Hordeum fragilis, Agropyron desertorum and Agropyron elongatum). A factorial experimental design based on completely Randomized Design with three replications was applied as the main factor included three rangeland species and the second factor included five salinity levels (0, 50,100,150 and 200 mMol NaCl). Salinity treatments were applied for 66 days and 27 variables were evaluated during the experiment. Results of analysis of variance showed significant differences among studied species and also different salinity levels. According to the results of means comparison test in 15 treatments (interaction effects of species and salinity), the highest RWC was observed in treatments of control (0 mM NaCl) and 50 mM NaCl in all three species and the lowest RWC was recorded at 200 mM NaCl in two Agropyron species. As a result, reduction in RWC was identified as plant response to salinity stress. The highest content of total chlorophyll was observed in control treatment and in two Agropyron species while the lowest content was recorded at 200 mM NaCl in all three species. With increase in salinity level up to 200 mM NaCl, soluble carbohydrate content increased. The highest percentage of proline was observed at 200mMol NaCl and in all three species. According to the results, threshold of salinity tolerance for Ag. elongatum, Ag. desertorum and Hordeum fragilis were determined 150, 100 and 50 mM NaCl respectively, and Ag. elongatum was identified as the most salt tolerant species in this research. A significant positive correlation was observed among growth parameters while correlation between growth parameters and carbohydrate content and percentage of proline was significantly negative. Total chlorophyll content showed a significant positive correlation with RWC and a significant negative correlation with WSD, soluble carbohydrates content and percentage of proline.
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