Effects of dry-direct seeding with non-flooded regime on starch structure and functionality in water-saving and...

Water scarcity challenges sustainable rice production, necessitating water-saving strategies like dry-direct seeding with non-flooded (DSN) regimes. In this study, two-year field experiments were conducted using water-saving and drought-resistance rice (WDR) Hanyou 73 (HY73) and drought-sensitive Huazheyou 1 (HZY1). Under the DSN regime, both varieties exhibited a significant increase in the proportion of short branches and a decrease in long branches of amylopectin, resulting in reduced relative crystallinity and increased amorphous regions. This ultimately led to lower gelatinization temperature and setback viscosity, and higher breakdown viscosity. Meanwhile, the DSN regime increased the number of small starch granules, enhancing swelling power, solubility, and digestibility. Compared with HZY1, HY73 maintained a more stable chain length distribution and physicochemical properties under the DSN regime, exhibiting more suitable thermal and pasting characteristics. This study provides a theoretical basis for the promotion of WDR varieties under dry cultivation conditions.