The productivity of a crop such as wheat, as the main food of a major part of the world, is seriously threatened in areas where the soil or the irrigation water is relatively salty. Salinity stress by applying the primary effects of ionic toxicity and osmotic stress and the secondary effects of oxidative stress affects a set of pathways and processes of gene expression, signaling, biochemistry and physiology of the plant, which leads to a decrease in plant performance. On the other hand, lack of zinc (Zn) caused by insufficient dietary intake is a global nutritional challenge, especially in developing countries, and the biological enrichment of wheat with zinc micronutrients is a high-priority research work. Today, after the rediscovery of the positive characteristics of the indigenous populations, especially the ancient wheats, such as the tolerance of various stresses and the high quality of their grains, they have become popular. Therefore, the present study eva‎luates the hulled (ancient) and modified naked (modern) varieties of wheat in terms of agronomic, physiological and molecular responses to salinity stress (0, 75 and 150 mM NaCl) and also foliar-applied Zn (spraying 0 and 4 gram per liter of zinc sulfate solution (ZnSO4.7H2O)). The first experiment was carried out in pots from mid-November to mid-July (2018-2019) for the screening of 18 genotypes of hulled and non-hulled wheat at three irrigation water salinity levels of 0, 75 and 150 mM NaCl with three replications (a factorial exeriment based on completely randomized design) in the Chah-anari Research and Training farm of Isfahan University of Technology. The second experiment was carried out in field conditions in two cropping seasons of 2019-2020 and 2020-2021 in two environments with non-saline and saline irrigation of 150 mM NaCl. In each environment, two levels of foliar spraying of 0 and 4 g/L of zinc sulfate and ten selected genotypes from the first experiment were used in three replications (a split-plot-factorial based on a randomized complete block design) in Lavark Research Farm in Najafabad. The third experiment was carried out hydroponically in the controlled environment of the greenhouse, where four selected genotypes from previous studies were subjected to 150 mM NaCl salinity in three replicates (a factorial based on completely randomized design) to investigate the expression of genes related to ion homeostasis in perlite substrate. The results showed that salinity stress, especially the level of 150 mM, caused a severe drop in grain yield in modern genotypes. On the other hand, some ancient genotypes were tolerant to salinity. Physiological mechanisms of salinity tolerance discovered in this experiment for ancient genotypes were preservation of relative water content and potassium concentration of leaves, accumulation of compatible organic matter proline for osmotic regulation and strong antioxidant activity. Also, the specific mechanisms of salinity tolerance in the ancient emmer genotypes include tissue tolerance, i.e. the accumulation of sodium in the leaf to create osmotic balance and its transfer to a less dangerous place to prevent ion toxicity, and for the ancient spelt genotypes, it includes preventing sodium from entering the aerial part for inhibit ion toxicity. At the molecular level, it was also observed that when exposed to salinity, the spelt increased the expression of the SOS1 gene (high sensitivity to salinity) and the emmer increased the expression of the NHX1 gene (transfer of sodium into the vacuole). In the assessment of grain quality characteristics, it was also found that ancient wheat genotypes, especially emmer, had better grain quality in terms of grain protein and zinc content, grain hardness, gluten content, gluten index and water absorption rate compared to modern genotypes. In addition, foliar application of zinc sulfate strengthened all the investigated quality traits in both saline and non-saline conditions.

پرويز احسان زاده

احمد ارزاني , محسن اسماعيل زاده مقدم

حسن كريم مجني , حسين شريعتمداري , سينا فلاح