Metabolite accumulation contributes to differences in seed germination of water-saving and drought-resistance rice under dry direct seeding

Dry direct seeding of rice has emerged as an effective method for reducing the excessive water demand associated with conventional rice transplantation, presenting significant potential for enhancing sustainability. However, this cultivation method is hindered by high seed usage and often inconsistent and low seedling emergence. Seed priming, a pre-sowing treatment, has been employed to mitigate these issues, but the inconsistent effects of exogenous priming agents remain a concern. Currently, there is limited molecular-level information on the uneven seedling emergence and effective screening methods for priming agents. In this study, we employed a metabolomics approach using advanced chromatography and mass spectrometry technology to identify differential accumulation of metabolites (DAMs) in seeds with varying germination energies. The seed priming technique was also used to validate the identified DAMs. We investigated the proportion of different specific gravity seeds and the corresponding germination energy across 20 varieties and established a relationship between different specific gravity seeds and germination energy. Our results showed that seeds with high and low germination energy differed in several metabolites, including amino acids, organic acids, and others. We further confirmed the critical role of these DAMs in determining seed germination energy under dry direct seeding. This research provides valuable insights into the metabolic mechanisms associated with germination energy and offers a useful approach for screening effective endogenous seed priming agents.