淹水胁迫是导致直播稻成苗率低的主要因素。在淹水条件下，胚芽鞘仍能快速生长的优异种质，更适于水稻直播种植模式。同源四倍体水稻虽具有籽粒大、杂种优势强和胁迫耐受能力强等多倍化优势，但前期研究受制于其低育性。而新型四倍体水稻等种质克服了低育性瓶颈，且在胁迫耐受能力方面具有优势，有望成为耐淹新种质的筛选来源。本研究对380份新型四倍体水稻衍生品系进行了萌发期耐淹能力评价，筛选获得11份耐淹种质。在淹水8 cm条件下上述种质的胚芽鞘均能快速伸长，其长度显著长于对照H441，是对照的1.94~2.90倍。在进一步的土培淹水试验中，深度淹水条件下对照H441的成苗率显著降低至30.34%，而耐淹种质的成苗率仍达到45.34%~65.34%，与浅水条件下无显著差异。细胞学观察发现，耐淹种质胚芽鞘中部和尖端的细胞长度均显著长于对照；生理指标测定显示，淹水胁迫下耐淹种质胚芽具有更强的超氧化物歧化酶（superoxide dismutase，SOD）活性。此外，耐淹种质保留了新型四倍体水稻结实正常、籽粒大等优良性状。本研究建立了适用于四倍体水稻的耐淹种质筛选体系，所得优异种质可为后续多倍体水稻萌发期耐淹分子机理解析和新品种选育奠定基础。

Submergence stress is a major factor limiting the seedling establishment rate of direct-seeded rice, and elite germplasms with rapid coleoptile elongation under submerged conditions exhibits greater adaptability to direct-seeding systems. Autotetraploid rice possesses polyploidization advantages such as enlarged grains, strong heterosis, and enhanced stress tolerance; however, its low fertility has constrained its research and application. The emergence of fertile neo-tetraploid rice, which overcomes the sterility bottleneck and retains the above-mentioned polyploidization advantages, holds promise as a source for elite submergence-tolerant germplasm. In this study, 380 neo-tetraploid-derived lines were evaluated for submerged tolerance during germination, and 11 tolerant accessions were identified. Under submergence stress (8 cm depth of water), the coleoptiles of these accessions elongated rapidly, reaching lengths 1.94‒2.90 times that of the control variety H441. In subsequent pot soil submerged assays, deep submergence significantly reduced the seedling establishment rate of the control H441 to 30.34%, whereas the tolerant lines maintained seedling establishment rate of 45.34%‒65.34%, comparable to shallow-water conditions. Cytological observations revealed that cell lengths in both the middle and tip regions of the coleoptiles were significantly greater in the tolerant accessions than in the control. Physiological measurements indicated that the coleoptiles of tolerant accessions exhibited higher superoxide dismutase activity under submergence stress. In addition, the tolerant lines retained desirable agronomic traits of neo-tetraploid rice, including normal seed setting and relatively large grain size. This study establishes a screening system for submergence-tolerant germplasm in tetraploid rice, and the elite accessions obtained provide valuable materials for future investigations into genetic mechanisms underlying submergence tolerance and for breeding submergence tolerant polyploid rice varieties.