Elevated carbon dioxide offers promise for wheat adaptation to heat stress by adjusting carbohydrate metabolism.

Carbohydrate metabolism in plants is influenced by thermodynamics. The amount of carbon dioxide (CO2) in the atmosphere is expected to rise in the future. As a result, understanding the effects of higher CO2 on carbohydrate metabolism and heat stress tolerance is necessary for anticipating plant responses to global warming and elevated CO2. In this study, five wheat cultivars were exposed to heat stress (40 °C) at the onset of anthesis for three continuous days. These cultivars were grown at two levels of CO2 i.e. ambient CO2 level (a[CO2], 380 mmol L-1) and elevated CO2 level (e[CO2], 780 mmol L-1), to determine the interactive effect of elevated CO2 and heat stress on carbohydrate metabolism and antioxidant enzyme activity in wheat. Heat stress reduced the photosynthetic rate (Pn) and grain yield in all five cultivars, but cultivars grown in e[CO2] sustained Pn and grain yield in contrast to cultivars grown in a[CO2]. Heat stress reduced the activity of ADP-glucose pyrophosphorylase, UDP-glucose pyrophosphorylase, invertases, Glutathione reductase (GR), Peroxidase (POX), and Superoxide dismutase (SOD) at a[CO2] but increased at e[CO2]. The concentration of sucrose, glucose, and fructose mainly increased in tolerant cultivars under heat stress at e[CO2]. This study confirms the interaction between the heat stress and e[CO2] to mitigate the effect of heat stress on wheat and suggests to have in-depth knowledge and precise understanding of carbohydrate metabolism in heat stressed plants in order to prevent the negative effects of high temperatures on productivity and other physiological attributes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01080-5. © Prof. H.S. Srivastava Foundation for Science and Society 2021.