The increase in atmospheric carbon dioxide (eCO2) concentrations and rising temperature has emerged as a significant concern due to its potential implications for humankind, particularly in terms of jeopardizing food and nutritional security. The present study aimed to investigate the effects of eCO2 and terminal heat stress (HS) on grain quality in wheat. We assessed the grain quality in four different wheat cultivars: HD2967 (thermotolerant), HD2329 (thermo susceptible), HI1500, and GW322 (nitrogen responsive). HD2967 demonstrated a more favourable response to heat stress compared to the other genotypes. Additionally, we observed a positive impact of eCO2 on starch content, maximum in HD2967 (74%), whereas heat stress led to a decrease in starch content across all genotypes, albeit with minimum starch content in the thermo susceptible genotype i.e., HD2329 (57%). Moreover, our study demonstrated that eCO2 enhanced the accumulation of total soluble sugar and reducing sugar. Additionally, a significant increase in total soluble protein and free amino acid content were observed in all genotypes under combined stress. These findings highlight the potential of these genotypes, particularly the thermotolerant one, for breeding programs aimed at developing high-yielding and thermotolerant wheat cultivars under eCO2 and heat stress conditions.
