Abstract

Rice breeding programs require the integration of high yield potential with desirable grain quality traits. This experiment aimed to evaluate physical grain quality and gelatinization temperature of F₅ lines developed from the hybrid rice cultivar RDH3 after successive selfing and selection for plant type and yield performance. A total of 23 selected F₅ lines were analyzed for grain physical characteristics, including grain length, grain width, length-to-width ratio, and grain shape, together with gelatinization temperature determined using the alkali test. The results showed that most F₅ lines possessed long to very long grains and were classified as slender grain types, with length-to-width ratios ranging approximately from 3.6 to 4.9, indicating good stability of grain physical traits at advanced generations. In terms of gelatinization temperature, the majority of the rice lines exhibited low gelatinization temperature, while some lines showed intermediate to high gelatinization temperature, reflecting the existing variation of starch-related traits within the selected population. Overall, the selected F₅ rice lines derived from RDH3 demonstrated favorable physical grain quality and diverse gelatinization temperature profiles, providing valuable information for further selection and development of promising rice lines for future varietal improvement.