Abstract：
Species producing seeds with a water-impermeable seed coat, i.e., physical dormancy (PY), dominate the dry tropical forests. Despite increasing interest and understanding of the germination ecology of a PY species, less is known about how PY break occurs, particularly what changes lead to the opening of the \'water gap\'. Based on the moisture conent (MC) attained, two ranges of PY may exist: shallow PY, a state with higher MC and seeds could reverse to a permeable state when the relative humidity increases; and absolute PY, a completely dry state. Here, we demonstrate that this MC variation between seeds affects preconditioning and the \'water-gap\' opening stages. A conceptual model developed shows a strong relationship between temperature and duration, with high temperature breaking PY in seconds, but seasonal temperature fluctuations and constant temperatures require a longer time. The duration required at any conditions to break PY is purported to depend on the hydrophobic bonds of the lipids, which are likely weakened during the preconditioning, and the amount of water influences hydrolysis, leading to the \'water-gap\' opening. We argue that the moisture content of the seeds and its interaction with biochemical compounds are a possible explanation for why only a proportion of PY seeds become permeable to water each year. Nonetheless, empirical investigations must validate these notions.
摘要：
产生具有不透水种皮的种子的物种，即，物理休眠（PY），主导着干燥的热带森林。尽管人们对PY物种的发芽生态学越来越感兴趣和了解，人们对PY断裂是如何发生的知之甚少，特别是什么变化导致了“水隙”的打开。根据获得的水分含量(MC)，PY可能存在两个范围：浅PY，当相对湿度增加时，MC和种子较高的状态可能会逆转为可渗透状态；而绝对PY，完全干燥的状态。这里,我们证明了种子之间的MC变化会影响预处理和“水隙”开放阶段。开发的概念模型显示了温度和持续时间之间的强关系，随着高温在几秒钟内打破PY，但是季节性的温度波动和恒定的温度需要更长的时间。在任何条件下破坏PY所需的持续时间据称取决于脂质的疏水键。在预处理过程中可能会减弱，水的量会影响水解，导致“水缺口”开口。我们认为，种子的水分含量及其与生化化合物的相互作用是为什么每年只有一部分PY种子变得透水的可能解释。尽管如此，实证调查必须验证这些概念。
