Abstract: Seed storability is a critical factor influencing the long-term viability of seeds in genebanks. However, evaluating seed storability remains challenging, as current methods such as viability loss curves are time-consuming and require significant seed resources. This study investigated the role of phenotypic and physiological factors in seed storability using 56 japonica rice seed samples with initial germination rates exceeding 90%. Our analysis revealed that phenotypic traits, such as 1000-grain weight, grain width, and length-to-width ratio, did not significantly correlate with seed storability, highlighting the complexity of the relationship between phenotype and storability. Dynamic changes in antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and glutathione reductase (GR)] were analyzed, and a significant positive correlation was observed between POD activity and seed storability. POD activity remained relatively high in storage-tolerant seeds, whereas it decreased more sharply in storage-sensitive seeds. Gene expression analysis of 11 highly expressed POD genes in seeds further confirmed the relationship between POD enzyme activity and storability, with storage-sensitive seeds showing a greater decline in POD gene expression. A linear regression model constructed using POD activity and initial germination rate showed that POD activity could reliably assess seed storability, with an R² value of 0.919 for storage-tolerant seeds. Cluster analysis of 28 seed samples validated these findings, establishing a POD activity threshold of 12 000 U/mg protein in unaged seeds imbibed for 48 h as a key indicator for distinguishing storage-tolerant seeds. This study provides valuable insights into the physiological and genetic mechanisms underlying seed storability and offers a promising approach for rapidly assessing seed storability in genebanks. POD activity as a storability indicator in other crops need further investigation.

Key words: seed storability, japonica rice, peroxidase activity, antioxidant system, viability loss