Heat shock-stimulated germination is frequently considered a trait restricted to a few plant families with impermeable seed coats in the Mediterranean Basin. We aimed to ascertain this general idea by using 68 eastern Mediterranean plant taxa differing in growth form, dormancy type and geographic distributional range. We conducted a laboratory experiment including heat shocks (60, 80, 100, 120 and 140°C for 5 min) and a control treatment, and monitored germination for each species. Among the studied taxa, 24 (35%) showed a significant positive response for at least one of the treatments. Many Cistaceae and Fabaceae species showed a positive germination response to the heat shocks. However, we also observed heat shock-stimulated germination in the Brassicaceae, Malvaceae, Polygonaceae and Scrophulariaceae, and provided additional evidence for the Asteraceae, Lamiaceae, Liliaceae, Plantaginaceae and Rosaceae in the Mediterranean Basin. Distributional range and dormancy type were significant determinants of germination response to heat shocks whereas growth form and phytogeographic origin had lower and/or non-significant contribution. Species with wide or local distribution were less tolerant to moderate heat shocks than those with regional distributional ranges. Species with physically dormant seeds showed significantly more stimulated germination after heat shocks than those with permeable seeds. In conclusion, dormancy type is an important determinant of seed response to heat shock, and an association exists between distributional range and germination response to heat shocks. Our findings revealed that heat shock-stimulated germination is observed across a broader taxonomic spectrum in the Mediterranean Basin, including families not possessing physical dormancy.

中文翻译：

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地中海盆地植物热激萌发与生长形式、休眠类型和分布范围的关系

热激刺激发芽通常被认为是地中海盆地少数具有不透水种皮的植物科的性状。我们旨在通过使用 68 个东地中海植物分类群来确定这一总体思路，这些植物分类群在生长形式、休眠类型和地理分布范围上都有所不同。我们进行了一项实验室实验，包括热激（60、80、100、120 和 140°C 5 分钟）和对照处理，并监测每个物种的发芽情况。在研究的分类群中，24 个（35%）对至少一种处理表现出显着的阳性反应。许多 Cistaceae 和 Fabaceae 物种对热冲击表现出积极的发芽反应。然而，我们还在十字花科、锦葵科、蓼科和玄参科中观察到热激刺激发芽，并为地中海盆地的菊科、唇形科、百合科、车前草科和蔷薇科提供了额外的证据。分布范围和休眠类型是对热冲击发芽反应的重要决定因素，而生长形式和植物地理起源具有较低和/或不显着的贡献。与具有区域分布范围的物种相比，具有广泛或局部分布的物种对中等热冲击的耐受性较差。与具有渗透性种子的物种相比，具有物理休眠种子的物种在热冲击后表现出明显更多的刺激发芽。总之，休眠类型是种子对热激反应的重要决定因素，分布范围与萌发对热激反应的反应之间存在关联。