Growth performance and antioxidative response in bread and durum wheat plants grown with varied potassium treatments under ambient and elevated carbon dioxide

•Relation between antioxidant system and K deficiency were determined under elevated CO2 (e-CO2).•e-CO2 promoted biomass production with adequate K supply in bread and durum wheat species.•Low or deficient K induced oxidative stress, but e-CO2 had no impact on antioxidant response.•e-CO2 could not alleviate detrimental effects of K deficiency.•Response of antioxidant enzymes were linked to K status of plants rather than e-CO2 conditions.

It is predicted that atmospheric carbon dioxide (CO2) level will double by the end of the current century. Although the fertilization effect of CO2 on plant growth is well documented, studies that investigate plant nutritional requirements under elevated CO2 are scarce. Potassium (K) is an essential plant nutrient with prominent roles in key physiological processes. Aim of this work, was to determine the effects of K deficiency on plant growth as affected by elevated CO2 and how antioxidant defense systems (activities of SOD, CAT, POX, APX, GR, MDHAR, DHAR, lipid peroxidation and total antioxidant activity) respond to K deficiency under ambient (a-CO2: 400 ppm) or elevated (e-CO2: 900 ppm) atmospheric CO2 conditions in durum (Triticum durum cv. Sarıçanak-98) and bread wheat (Triticum aestivum cv. Adana-99). Plants were grown in hydroponics with sufficient (1850 μM), low (60 μM) or deficient (20 μM) K and under a-CO2 or e-CO2. As expected, e-CO2 promoted biomass production with adequate K supply, however in low and deficient K plants biomass was either not affected or even decreased by e-CO2. It was observed that low or deficient supply of K induced oxidative stress, but e-CO2 had no significant impact on antioxidative response of plants and thus could not alleviate detrimental effects of K deficiency. Under K deficiency, CAT activity decreased in both species but this decrease was accompanied with increases in POX and APX which may be for adapting to the changing environment. In general, responses in antioxidant defense enzymes were linked to K nutritional status of plants rather than e-CO2 conditions.