Document Type : Original Article
Department of Nature engineering, University of Kashan, Iran
The Resistance to environmental salinity in rangeland plant species has different mechanisms, and one of the most effective factors in this field is different phenological stages. In The current study salinity tolerance of one rangeland's species (Agropyron desertorum) at different phenological stages was examined. The treatments included five saline irrigation levels: 0.50 (Well water as control), 2, 4, 8 and 10 dS m-1 and three phenological stages at which salinity was applied: Germination, (2-leaf), flowering and before seeding. Growth parameters, ions accumulation and oxidative effects in this rangeland's spices were evaluated. According to the results, the effect of salinity varied from phenological stages and a significant reduction in plant shoot and root dry weights, root length, height, and potassium (shoot and root) concentration was observed under salinity stress. Also, tissue sodium concentration and antioxidant enzymes activities were enhanced due to salt stress.The negative effects on growth parameters and biochemical attributes were quite evident in higher levels of salinity. The salt stress at the early phenological stage had a more severe effect on plant growth than that applied at the later phenological stages. Based on Van-Genuchtan and Hoffman equation, the salt tolerance threshold analysis worked out as 50% reduction of Agropyron desertorum that were 6.50, 7.98 and 10.00 dS m-1 at germination, (2-leaf), flowering and before seeding, respectively. However, the plants were able to recover in terms of accumulation of ion and antioxidant enzymes as well as those without stress when salt stress was introduced at the seed germination stage. Overall, Agropyron desertorum has been shown to have a sensitivity at early phenology and relatively tolerance in subsequent phases of development.