Consuming rice with low starch digestibility is beneficial for reducing the risk of diabetes. Several factors have been shown to influence starch digestibility, but the combined effects of these factors on starch digestibility have not been studied. We assessed multidimensional relationships between the glucose production rate (GPR) of cooked rice with 16 indexes, including physicochemical, pasting and textural properties in 30 rice varieties. The stepwise multiple regression analysis showed that amylose content (AC), gel consistency (GC) and pasting temperature (PT) were closely related to GPR. This relationship could be described by the equation: GPR = −0.080 AC + 0.008 GC + 0.034 PT + 0.720, with a determination coefficient of 0.84. The variation partitioning analysis further indicated that AC, GC and PT independently explained 36%, 5% and 4% of the GPR variation, respectively. The interaction of AC and GC explained 46% of the variation in GPR. This study identifies the key indexes (AC, GC and PT) affecting starch digestibility and quantifies contributions of these indexes to the variation in GPR. The finding of our study provides useful information for breeding and selecting rice varieties with low GPR.

In order to identify the influence of climatic conditions of different rice-growing seasons on cooking quality of the rice noodles, a field experiment was conducted in Liuyang, Hunan Province from 2020 to 2022. Five noodle rice cultivars (Guanglu’ai 4, Zhongjiazao 17, Xiangzaoxian 24, Zhongzao 39, and Zhuliangyou 729), were grown in the early and late seasons to compare the cooking quality of rice noodles and the grain quality of noodle rice. The results showed that the mean temperature and solar radiation at grain-filling stage were 18.7% and 12.7% lower in the late season than in the early season, respectively. The cooking loss rate of rice noodles was reduced by 7.4% in the late season compared to the early season. There were not significant differences in cooked break rate and water absorption rate between early and late seasons. The peak viscosity, through viscosity, breakdown viscosity, final viscosity, consistency viscosity, and pasting temperature were lower by 25.8%, 22.9%, 34.3%, 19.7%, 14.2%, and 2.0%, whereas the setback viscosity and peaking time were higher by 11.8% and 2.3% in the late season compared to the early season, respectively. Correlation analysis showed that the mean temperature at grain-filling stage was positively correlated with peak viscosity, through viscosity, breakdown viscosity, final viscosity, consistency viscosity, and pasting temperature, and negatively correlated with setback viscosity. The mean radiation at grain-filling stage was positively correlated with peak viscosity, through viscosity, final viscosity, and negatively correlated with setback viscosity. The cooking loss rate of rice noodles was positively correlated with the final viscosity, pasting temperature, and peaking time. Therefore, the cooking quality of rice noodles can be improved by growing noodle rice in the late season. The final viscosity and pasting temperature in the paste properties of noodle rice were the critical factors affecting the cooking loss rate of rice noodles.