Water stress is one of the main abiotic stresses that reduce plant growth;this decrease is due to changes such as physiological changes and causes growth and production limitation that caused by drought stress.In order to evaluate the effects of drought stress on some morphological and physiological characteristics of tow wheat cultivars, a factorial experiment based on completely randomized design was conducted. The findings show that drought stress exacerbations result in the plant's response to stress due to increased wheat resistance. This response is due to changes in plant pigments, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase and malondialdehyde, glucose, galactose, rhamnose and xylose, which ultimately influence these changes effects on the morphological characteristics of wheat.Drought stress reduces the concentration of carotenoids, chlorophyll a, chlorophyll b, total chlorophylls, but glucose, galactose, rhamnose, xylose, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase, malondialdehyde (in leaves and roots) and the chlorophyll a and b ratios were increased.Reduction of plant height, stem height, root length, fresh and dry weight of wheat treated with 250 g / l PEG compared to non-treatment were 0.264, 0.236, 0.394, 0.183 and 0.395, respectively.From the two wheat cultivars, the morphological characteristics of the N8720 increased compared to the Gonbad cultivar. Interaction effects of cultivar and drought stress showed that N8720 cultivar without treatment had the highest morphological characteristics, carotenoid concentration, chlorophyll a, chlorophyll b, total chlorophylls a and b, and the above cultivar with 250 g / l PEG (drought stress) had the highest amount of proline, malondialdehyde, soluble sugars and enzymes in leaves and roots. Increasing activity of oxidative enzymes and soluble sugars in wheat under drought stress could be a sign of their relative tolerance to drought stress.
