In recent years, global efforts even in developing countries have been focused on mitigating the negative effects of climate change. In this regard, the occurrence of drought stress concurrent with risingatmosphericcarbon dioxide concentration is one of the most important challenges in the production of field crops such as wheat. Therefore, it is necessary to identify the responses of the wheat cultivars to the inevitable climate change in a mechanistic level. The present study was conducted to investigate the morphological, physiological and, biochemical responses of 23 wheat cultivars to different irrigation regimes (40% MAD "control", 75% MAD " water deficit stress") as thefactorial experiment arrangedin acompletely randomized design with three replications under two separate environments (ambient (400±50) and elevated air carbon dioxide concentrations (700±50 µmol mol -1 ) in 2017 at the greenhouses of Isfahan, Iran. The results showed that the elevated vs. ambient CO 2 increased averaged plant seed weight by 9 and 13% in normal and water deficit conditions, respectively. Elevated CO 2 had a significant positive effect on seed weight of ‘Alamut’, ‘Karaj’, ‘Marvdasht’, ‘Shiraz’, ‘Tajan’ and ‘Yavaros’ cultivars under normal irrigation conditions, but such an effect was not seen in other cultivars. However, the positively significant effects of elevated CO 2 was observed in studied wheat cultivars except for ‘Arg’, ‘Roshan’, ‘Sepahan’, ‘Shahriar’, ‘Sholeh’, ‘Sorkhtokhm’, ‘Yavaros’ and Hidhub, under water deficit condition. By increasing the CO 2 concentration, the average shoot dry weight of wheat cultivars increased by 49% and 34% under normal and water deficit conditions, respectively. The highest and lowest mean increase were observed in ‘Sholeh’ and ‘Karaj’, respectively, under normal irrigation (102 and 9%) and in ‘Sholeh’ and ‘Kavir’ respectively, under water deficit condition (94 and 4%). Under normal irrigation, elevated CO 2 increased the plant root weight (PRW) (78%),oluble sugar concentration (SSC) (31%), photosynthesis (A) (54%), intercellular CO 2 concentration (Ci) (21%), stomatal conductance (gs) (20%), Fv/Fm (0.4%) and plant leaf area (PLA) (16%), but it decreased malondialdehyde concentration (MDA) (30%), proline (Prol) (28%), catalase enzyme activity (CAT) (21%), ascorbate peroxidase enzyme activity (APX) (18%), guaiacol peroxidase activity (GPA) (20%), DPPH radicalcavengingactivity (DPPH) (11%), trairation (T) (20%), chlorophyll a ( Chla ) (20%), chlorophyll b ( Chlb ) (38%), carotenoids ( Car ) (27%) and plant height (PH) (3%). Under water deficit condition, elevated CO 2 increased PRW (50%), SSC (25%), A (35%), ci (21%), gs (27%), Fv/Fm (0.4%), PLA (24%), PH (7%), but it decreased MDA (30%),Prol (28%), CAT (21%), APX (20%), GPX (18%), DPPH (17%), T (31%), Chla (29%), Chlb (43%) and Car (35%). Generally based on the obtained results it could concluded that the amount and type of effects of elevated CO 2 on wheat growth vary with soil moisture condition and wheat cultivar. In addition, there was a considerable variation among the studied cultivars in terms of the examined characteristics rendering them potent to be used to improve the production efficiency of this staple crop species under climate change conditions. Keywords: Carbon dioxide, Climate Change, Chlorophyll b , DPPH radicalcavengingactivity, Genetic Diversity, Leaf stomatalconductance, Wheat.