In wetlands, dormancy may be a key functional trait enabling seeds to avoid underwater germination, which could be lethal for seedling establishment. Our objectives were to find out (i) if shallow dormant (i.e. conditionally dormant) Echinochloa crus-galli seeds from an anaerobic germination resistant accession can break dormancy under hypoxic submergence and (ii) if underwater germination can be restored in scarified, non-dormant seeds. Shallow dormant E. crus-galli seeds perceived diurnally alternating temperatures (AT) and red light (R) pulses (i.e. dormancy-breaking cues) under hypoxic submergence; however, an inhibitory far-red light pulse given at the end of the 4-d inundation period demonstrated that most of the seeds (85%) were unable to break dormancy. Scarified E. crus-galli seeds, which did not express dormancy under drained conditions, were unable to germinate under hypoxic submergence, despite being exposed to dormancy-breaking cues (AT + R). Lastly, the temporal window for germination sensitivity to the inhibitory action of hypoxia, once dormancy-breaking signals have been applied, is progressively lost and bounded to approximately 18 h for half of the seed lot. These results highlight the importance of dormancy as a trait enabling E. crus-galli seeds to avoid underwater germination, a risky scenario for seedling emergence and establishment in this facultative hydrophyte.

中文翻译：

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来自抗厌氧萌发的种质稗草种子的低氧浸水严格控制休眠破坏和萌发

在湿地中，休眠可能是使种子避免水下发芽的关键功能性状，这对幼苗的建立可能是致命的。我们的目标是找出 (i) 是否处于浅休眠状态（即有条件地处于休眠状态）稗草厌氧发芽抗性种质的种子可以在缺氧淹没下打破休眠，并且（ii）如果可以在划痕的非休眠种子中恢复水下发芽。浅休眠E. crus-galli种子在缺氧淹没下感知到昼夜交替的温度 (AT) 和红光 (R) 脉冲（即打破休眠的线索）；然而，在 4 天淹没期结束时发出的抑制性远红光脉冲表明，大多数种子 (85%) 无法打破休眠状态。划痕E. crus-galli在排水条件下不表达休眠的种子，尽管暴露于打破休眠的线索（AT + R），但在缺氧淹没下无法发芽。最后，一旦施加了打破休眠的信号，发芽对缺氧抑制作用的敏感性的时间窗口就会逐渐消失，并且对于一半的种子批次来说，大约为 18 小时。这些结果突出了休眠作为一种特征的重要性E. crus-galli种子以避免水下发芽，这是在这种兼性水生植物中出苗和建立的危险场景。