The Response of Wheat Cultivars to the Elevated Concentration of Air Carbon Dioxide and Salinity

This experiment was conducted in a greenhouse at Isfahan University of Technology, Isfahan, Iran in 2014 to evaluate 20 wheat cultivars (Navid, Pishtaz, Karaj, Kavir, Tajan, Karun, sholeh, Bahar, Khoshki 11, Gasparood, Sepahan, Sorkh tokhm, Chamran, Ghods, Shariar, Omid, Sistan, Alamut, Marvdasht and Shiraz) under two carbon dioxide concentrations (the ambient 360 and the enriched 700 µM) and two salinity levels (0 and 150 mM NaCl). Treatments were arranged as a factorial in a completely random design with three replications. The results showed that salinity decreased potassium concentration in shoots (27%) and roots (39%), chlorophyll a and b concentrations (27 and 30%, respectively), carotenoids concentration (21%), plant height (39%), leaf area (32%), root volume (40%), shoot and root dry weight (30% and 23%, respectively); however, it increased sodium concentration in the shoots and roots (36%). The extent of salt-induced decreases in the shoot dry weight of the evaluated cultivars ranged from 8 to 46%. Karaj and Marvdasht cultivars were the most and the least sensitive cultivars to salinity under both ambient and enriched carbon dioxide concentrations, respectively. The elevated carbon dioxide concentration increased potassium concentration in the shoots (except Sholeh, Ghods and Gasparood) and roots, chlorophyll and carotenoids concentrations, plant height, leaf area (except Shahriar), root volume, shoot (except Sistan and Omid), and root dry weight; however, it decreased sodium concentration in the shoots and roots. The highest and the lowest increases in the shoot dry weight under non saline condition were obtained for Karaj and Alamut (23 and 6%, respectively); under saline conditions, they were found in Chamran and Kavir (66 and 3%, respectively). The results obtained from this experiment showed that the elevated carbon dioxide concentration positively influenced the growth of most cultivars. This effect was more pronounced under saline conditions, indicating that carbon dioxide enrichment could alleviate, at least in part, the negative effects of salinity.