Elevated atmospheric CO₂ concentration enhances the cooking and eating quality of hybrid rice by modifying starch...

Elevated atmospheric CO₂ concentration (eCO₂) is a key driver of climate change, influencing crop yield and quality. However, its effects on the cooking and eating quality (CEQ) of hybrid rice remain unclear. This study investigates eCO₂'s effect on CEQ by conducting a field experiment from 2015 to 2017 with three popular varieties grown in a free-air CO₂ enrichment platform. eCO₂ enhanced the volume and surface area of starch granule due to the formation of additional dents and holes on its surface upon eCO₂, thereby altering its morphology and potentially influencing starch-protein interplay. It also induced significant changes in starch molecular structure, including increases in blue value (22.4 %), iodine binding power (5.7 %), and amylose content (5.5 %), while protein concentration decreased. These changes led to improvements in pasting (11.0 % increase in breakdown) and thermal properties (ΔHgel increased by 15.6 %), ultimately enhancing the rice taste by 8.5 %. Statistical analysis indicates that these improvements were primarily driven by eCO₂-induced changes in starch granule structure. Indica-hybrid rice exhibited a greater response to eCO₂, which was influenced by environmental conditions. This study provides valuable insights into how eCO₂ affects hybrid rice CEQ, highlighting the need to consider varietal and environmental factors when developing climate adaptation strategies.