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

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.