A Novel Rice Seed Vigor Assessment Method Based on Simulated "Stifled Seed" Composite Stress for Predicting Field Emergence in Direct-Seeded Rice

The transition from transplanting to direct-seeded rice (DSR) systems necessitates high-vigor seeds capable of rapid establishment under complex field conditions. However, the Standard Germination Test (SGT) often overestimates field performance, while emerging optical detection technologies remain cost-prohibitive for widespread adoption. Inspired by the "stifled seed" phenomenon—a common agricultural issue where poor ventilation during seed priming leads to viability loss—this study developed a novel, low-cost vigor test simulating composite abiotic stresses. Rice seeds ( Oryza sativa L.) were subjected to 24 h imbibition followed by a controlled stress treatment of hypoxia, high temperature (40 °C), and high humidity for 36 h, prior to standard germination. Results from 16 diverse rice varieties showed that while SGT indices remained uniformly high, the vigor indices obtained after the composite stress treatment exhibited significant variation closely mirroring field performance. Regression analysis revealed that Germination Energy and Germination Percentage from this new method were highly predictive of field emergence ( R 2 =0.699 and 0.837, respectively, p <0.0001), significantly outperforming SGT. By effectively integrating the physiological pressures of anaerobic and hydrothermal stress, this method provides a robust, accessible, and accurate tool for seed quality grading and variety screening in DSR production, bridging the gap between laboratory potential and field reality. • Simulated "stifled seed" stress accurately differentiates rice seed vigor levels. • Superior prediction of field emergence ( R 2 =0.837) over standard germination test. • Robust, low-cost alternative to expensive optical methods for seed testing.