Effects of water management and variety type on grain yield and quality in ratoon rice

To evaluate the effects of water-saving irrigation and variety type on grain yield and quality in ratoon rice, field experiments were conducted in Qichun and Xishui, Hubei province, in 2023. Three water-saving and drought-resistant rice (WDR) varieties (Hanyou 8200, Hanyou 116, and Hanyou 73) and three superior-quality rice (SQR) varieties (Zhenliangyouyingxiangsimiao, Quanyouyuenongsimiao, and Quanyou 607) were tested, with Liangyou 6326—commonly grown in large-scale ratoon rice production in Hubei—serving as the check variety for ordinary paddy rice (OPR). Two irrigation regimes, continuous flooding and water-saving, were compared to assess varietal responses in yield and grain quality within the ratoon rice system. Results showed that, compared to continuous flooding, water-saving irrigation reduced water input by an average of 76% in the main crop and 85% in the ratoon crop, without significant differences in grain yield or in milling, appearance, and cooking/eating quality traits. These results were consistent across both experimental sites. WDR varieties maintained stable yield and grain quality under water-saving conditions. In SQR varieties, yields averaged 8.54 t hm^-2 in the main crop and 5.88 t hm^-2 in the ratoon crop, comparable to OPR. However, head rice rate significantly increased by 13.5 and 20.6 percentage points, while chalky grain rate and chalkiness degree decreased significantly by 22.6 and 6.4, and 10.8 and 1.8 percentage points, respectively, in the main and ratoon crops. For WDR varieties, yield and grain quality in the main crop were similar to OPR, but ratoon crop yield decreased significantly by 17%; nonetheless, head rice rate increased by 17.0 percentage points, and chalky grain rate and chalkiness degree decreased by 5.5 and 1.0 percentage points, respectively. Significant varietal differences were observed within each variety type for both yield and grain quality. Correlation analysis revealed positive associations between grain quality traits in the main and ratoon crops. Overall, in regions with favorable rainfall, combining superior rice varieties with a water-saving irrigation strategy that emphasizes rainfed cultivation supplemented by timely irrigation at critical growth stages can effectively reduce water use, improve water use efficiency, and achieve the dual goals of high yield and premium grain quality in ratoon rice systems.