Cacti are conspicuous plants across arid and semi-arid ecosystems of the American continent and are currently under threat due to human pressures, such as habitat loss, illegal collection and changes in fire regimes. Although much of their habitat is highly fire prone, there are strikingly few studies on their germination response to fire cues. The aim of this work was to analyse the effect of heat shock (simulating wildfires) on the ‘germination %’ and the ‘mean germination time’ of 13 cactus species of two growth forms (six columnar and seven globose) from a fire-prone cactus diversity hotspot in Córdoba Mountains, central Argentina. We also analysed the effect of growth form and seed mass on species responses. Seeds were subjected to the following treatments: 70°C/5 min, 70°C/10 min, 105°C/5 min, 105°C/10 min and a control (i.e. no heat). Germination decreased under at least one treatment in seven species, increased in three species, had contrasting changes in one species, and showed no effect of treatments in two species. Germination was faster in eight species, slower in one species and showed no effects of treatments in four species. Germination was significantly higher for globose species following the 70°C/10 min treatment and for columnar species under the treatment of 110°C/10 min; while germination time did not differ between growth forms. Seed mass did not have a significant effect on germination, and only affected germination time under the 70ºC treatments, under which lighter seeds germinated faster than heavier seeds. Our results show that the studied species exhibited a high diversity of responses, with most of the species presenting tolerance to heat shock, and that under certain conditions growth form and seed mass are important traits related to species responses to heat shock treatments.

中文翻译：

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野火会影响仙人掌种子的发芽吗？实验评估

仙人掌是美洲大陆干旱和半干旱生态系统中引人注目的植物，目前由于栖息地丧失、非法采集和火势变化等人类压力而受到威胁。尽管它们的大部分栖息地都非常容易着火，但关于它们对火灾线索的发芽反应的研究却非常少。这项工作的目的是分析热休克（模拟野火）对 13 种具有两种生长形式（六柱状和七球状）的仙人掌的“发芽率”和“平均发芽时间”的影响。阿根廷中部科尔多瓦山脉的仙人掌多样性热点。我们还分析了生长形式和种子质量对物种反应的影响。对种子进行以下处理：70°C/5 分钟、70°C/10 分钟、105°C/5 分钟、105°C/10 分钟和对照（即不加热）。7 个物种在至少一种处理下发芽减少，在 3 个物种中增加，在一个物种中发生对比变化，并且在两个物种中没有表现出处理的影响。八个物种的发芽速度更快，一个物种的发芽速度较慢，并且在四个物种中没有显示出处理的影响。球状物种在 70°C/10 分钟处理后和柱状物种在 110°C/10 分钟处理后的发芽率显着更高；而不同生长形式的发芽时间没有差异。种子质量对发芽没有显着影响，仅影响 70ºC 处理下的发芽时间，在这种情况下，较轻的种子比较重的种子发芽更快。我们的结果表明，研究的物种表现出高度多样性的反应，大多数物种对热休克具有耐受性，