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Published online by Cambridge University Press: 22 August 2025
Eclipta [Eclipta prostrata (L.) L.] is an important tropical weed that has recently emerged as a problematic weed in dry direct-seeded rice (Oryza sativa L.) (DSR) fields in China. Understanding its seed germination biology and ecology is crucial for developing integrated weed management strategies in the DSR system. Laboratory experiments were conducted to investigate seed germination of E. prostrata seeds under varying environmental conditions. Germination was greatest under alternating temperature regimes of 25/15 to 40/30 C, whereas it was significantly reduced at 20/10 C and completely inhibited at 15/5 C. Germination was also fully suppressed under continuous darkness, indicating strong light dependency. Eclipta prostrata seeds tolerated a broad range of pH values (4 to 10) with germination rates consistently greater than 95%. However, germination declined sharply under osmotic potentials, falling below 2% at −0.6 MPa, and being completely inhibited at −0.7 MPa. Seeds also showed moderate salt tolerance, with 50% inhibition at 150 mM NaCl and no germination at 300 mM NaCl. Exposure to radiant heat (>90 C for 5 min) prevented germination, suggesting residue burning may be an effective control measure. Seedling emergence was highest (100%) on the soil surface but declined steeply with increasing burial depth, with no emergence observed beyond 0.5 cm. Similarly, surface application of wheat (Triticum aestivum L.) straw residue (2,000 to 6,000 kg ha−1) significantly reduced seedling emergence and biomass. These findings provide essential insights into E. prostrata germination ecology and offer practical implications for its integrated management in DSR systems.