Effects of irrigation regimes on starch structure and physicochemical properties of water-saving and drought-resistance rice

Abstract

Rice production in water-limited regions is increasingly constrained by drought and water-saving irrigation practices, which can compromise grain yield and quality by altering starch structure and functionality. The starch-structural basis underlying cultivar differences in yield and quality stability under different irrigation remains insufficiently understood. This study investigated and analyzed changes in grain starch structure, physicochemical properties, and grain yield and quality in two varieties, the water-saving and drought-resistance rice cultivar Hanyou 116 (HY116) and the drought-sensitive rice cultivar Xieheyou 836 (XHY836) grown under five levels of irrigation volume. The results showed that drought stress significantly reduced grain yield, head rice rate, starch content, and pasting properties in both cultivars, and altered starch chain length distribution and crystallinity. Compared with XHY836, HY116 consistently exhibited higher yield stability, better milling and appearance quality, smaller increases in retrogradation and digestibility, and smaller changes in starch structure regardless of irrigation. By maintaining a relatively stable starch chain length distribution and crystalline structure, HY116 showed an enhanced resilience of starch physicochemical properties under different irrigation levels, demonstrating superior quality stability.