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Introduction Chamerion angustifolium (L.) Holub is a species with potential ecological and horticultural value, yet its tolerance to drought stress during early life stages remains poorly understood. This study investigated the drought tolerance of C. angustifolium by evaluating its physiological responses at both seed germination and seedling growth stages. Methods Seed germination assays were conducted under osmotic stress induced by polyethylene glycol (PEG-6000) at six specific concentrations: 2%, 4%, 6%, 8%, 10%, and 12% (w/v), with ultrapure water serving as the control. Germination parameters, including germination rate, vigor, index, relative drought damage rate, and post-germination radicle and plumule lengths, were recorded. Additionally, the contents of soluble sugars and soluble proteins in the seeds were quantified. For the seedling experiments, drought stress was then initiated by precisely controlling and maintaining the soil water content (SWC) at three deficit levels: 30% ± 5%, 50% ± 5%, and 70% ± 5%, representing mild, moderate, and severe stress, respectively. Each stress level was applied for 5, 10, or 15 days, corresponding to short-, medium-, and long-term exposure. Seedlings maintained at 90% ± 5% SWC throughout the experiment served as the wellwatered control. Results (1) Under PEG-6000 solutions of varying concentrations and different stress durations, seed germination rate, relative germination rate, germination vigor, germination index, and the radicle andplumule growth of C. angustifolium were significantly lower than the control (P<0.05). Seeds failed to germinate at all under 12% concentration; As solution concentration increased and stress duration prolonged, both radicle and plumule lengths exhibited a decreasing trend after seedling emergence; Under PEG-6000 solutions of varying concentrations, both soluble sugar and soluble protein contents in C. angustifolium seeds were significantly higher than the control level (P<0.05). As stress duration increased, soluble sugar and soluble protein contents generally showed an upward trend across all PEG-6000 concentrations.(2) Under different drought stress treatments, the osmotic regulator content and antioxidant enzyme activity in C. angustifolium seedlings were significantly higher (P< 0.05) than in the control group. With prolonged stress duration, osmotic regulator content showed an upward trend, while antioxidant enzyme activity exhibited a downward trend. Conclusion In summary, C. angustifolium possesses a certain degree of drought tolerance, and short-term mild drought stress does not significantly affect seed germination or seedling growth.