Abstract: Seeds of Hypericum perforatum were germinated under factorial combinations of temperature (15–30 ℃) and osmotic stress (0–25% PEG-6000). Water-uptake kinetics at 25 ℃ displayed a triphasic pattern: rapid imbibition (0–4 h), deceleration (4–20 h) and saturation (20–30 h). Rising temperature shortened the lag phase and advanced germination onset; however, all germination metrics—percentage, energy, index, vigour, radicle and seedling length—reached maxima at 25 ℃ and declined sharply at 30 ℃. PEG-mediated drought progressively delayed and reduced germination, with 25% PEG imposing complete inhibition. Drought tolerance was temperature-dependent, peaking at 25 ℃. Radicle and seedling elongation were greatest at 20 ℃, significantly curtailed at 15 ℃ and 30 ℃, indicating a stimulatory-to-inhibitory transition with increasing temperature. Thus, seeds achieve full hydration within 20 h; 25 ℃ is optimal for germination, whereas 20 ℃ best supports seedling growth. The osmotic threshold lies at 25% PEG, and drought resistance is maximised under the optimal germination temperature.

Key words: Hypericum perforatum; water absorption pattern; temperature; drought stress; seed germination

摘要： 以贯叶金丝桃Hypericum perforatum种子为材料，设置不同温度及干旱条件下萌发试验，并于室温(25 ℃)下观察种子动态吸水规律。结果表明，贯叶金丝桃种子吸水率变化呈现出“快速(0～4 h)—缓慢(4～20 h)—饱和(20～30 h)”规律。随温度升高种子发芽起始时间提前，发芽率、发芽势、发芽指数、活力指数、根长、苗长等发芽指标呈先增后降趋势，且均在25 ℃时达最大值。随PEG浓度增加种子萌发质量降低，发芽启动时间延长，25% PEG抑制种子萌发。种子萌发期抗旱能力受温度影响，适宜温度25 ℃时种子抗旱性最强；温度对贯叶金丝桃幼苗胚根和苗长具显著调控效应。20 ℃处理下胚根与苗长达最大值；30 ℃高温显著抑制生长，15 ℃亦表现受限，随温度升高呈先促进后抑制趋势。研究表明，贯叶金丝桃种子浸泡20 h达到吸水饱和；种子萌发适宜温度为25 ℃，幼苗生长适宜温度为20 ℃；干旱承受PEG溶液浓度的阈值为25%，萌发适宜温度下种子抗旱性增强。

关键词: 贯叶金丝桃；吸水规律；温度；干旱胁迫；种子萌发