The decrease in seed vigor and grain quality during storage has become an increasingly critical issue due to the extended storage periods resulting from declining rice consumption and climate change in Korea. Despite its importance, few studies have investigated rice seed aging in a large number of Korean rice cultivars. In this study, 53 japonica rice cultivars were evaluated for seed germination, vigor, and grain quality-related traits under accelerated-aging conditions. Seed germination rate was evaluated 7 days after imbibition, following accelerated aging treatments at 42℃ and 95% relative humidity for 8, 12, and 16 days. The average germination rates were 72.9% in the control (0 d), 71.7% after 8 days, 59.0% after 12 days, and 5.6% after 16 days of treatment. Grain quality-related traits, including texture and pasting properties, were also evaluated in rice subjected to the accelerated aging treatment. Adhesiveness and stickiness decreased, whereas hardness and toughness increased, as seed aging progressed. Cluster analysis based on germination rates after accelerated aging identified three distinct clusters, with cultivars in Cluster 3 maintaining a high germination rate of 70.6% even after 12 days of aging, showing clear differences from the other clusters. A principal component analysis (PCA) was conducted to investigate the relationship between germination rate and grain quality-related traits. The results showed that the germination rate and hardness tended to be negatively associated across all three clusters. These results suggested that cultivars with higher germination rates tend to maintain a softer cooked rice texture after aging. Our results provide insight into the relationship between seed aging and grain quality, highlighting elite cultivars that maintain both germination ability and grain quality during storage as valuable resources for breeding programs.

The rice cultivar ‘Chamdongjin’ exhibits a distinctively large grain size and excellent eating quality but is weak with regard to pre-harvest sprouting (PHS), requiring genetic improvement. In contrast, the premium-quality rice cultivar ‘Younghojinmi’ exhibits strong PHS tolerance. This study conducted quantitative trait loci (QTL) analysis on PHS and low-temperature germinability (LTG) using recombinant inbred lines derived from a cross between ‘Chamdongjin’ and ‘Younghojinmi’ to elucidate the genetic factors. Thus, an elite line with improved PHS tolerance was selected. QTL analysis revealed that qPHS3 and qLTG3 were associated with PHS and LTG, respectively, and the candidate gene was identified as qLTG3-1. The loss-of-function allele qltg3-1 in ‘Younghojinmi’ enhanced PHS tolerance compared to the functional allele qLTG3-1 in ‘Chamdongjin,’ but it also showed a trade-off relationship by decreasing LTG. CY_RILs carrying qltg3-1 exhibited lower PHS and LTG rates of 17.9% and 41.6%, respectively, compared to 44.1% and 55.7%, respectively, for CY_RILs with qLTG3-1. The elite line, CY_RIL79, carrying qltg3-1, was selected from CY_RIL. This line was recognized for its PHS tolerance while maintaining the key agricultural traits of ‘Chamdongjin,’ thus designated ‘Jeonju697.’ ‘Jeonju697’ is expected to be utilized as a practical alternative for addressing the issue of enhancing PHS tolerance in ‘Chamdongjin’; however, considering its weak LTG, it is desirable to improve this trait through further breeding efforts.

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