Mudflats are exposed for short periods after flood water drawdown. They support fast-growing annual herbs with a ruderal strategy. To optimize their recruitment success, seeds of mudflat species germinate better under fluctuating temperatures, full illumination and aerobic environments that indicate the presence of optimal (non-flooded) conditions for plant growth and development. Here, we hypothesize that prior exposure of mudflat seeds to hypoxic (flooded) environment interferes with the germination process and results in more vigorous germination once aerobic conditions are regained. To test this hypothesis, seeds of five mudflat species were incubated in both aerobic and hypoxic environments at four (14/6, 22/14, 22/22 and 30/22°C) temperature regimes, reflecting different (seasonal) conditions when drawdowns may occur. All species responded positively to four temperature regimes; however, moderate 22/14 and 22/22°C temperatures were optimum for high percentages and rates (speed) of seed germination. Since seeds of four species germinated exclusively under aerobic conditions, they were moved from hypoxic to aerobic conditions. Prior exposure of seeds to hypoxic environment facilitated high percentages, rates and synchronization of germination of Limosella aquatica, Peplis portula and Samolus valerandi seeds compared to incubation under strict aerobic conditions. However, prior exposure to hypoxic environment induced secondary dormancy in non-dormant seeds of Hypericum humifusum but broke dormancy in Lythrum hyssopifolia seeds that otherwise required cold stratification to overcome physiological dormancy. All species that have a narrow ecological niche (strictly occurring in mudflat habitats) showed positive responses to prior exposure to hypoxic environments. In contrast, H. humifusum that has a wide ecological niche (from mudflats to moist sandy grasslands) showed a negative response. We conclude that the hypoxic environment may strongly affect seed germination behaviour once the aerobic environment is regained. The most striking effect is the acceleration of the germination process and, therefore, life cycle supporting the survival in an ephemeral habitat.

中文翻译：

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泥滩物种的种子萌发对先前暴露于缺氧（洪水）环境的反应不同

洪水下降后，泥滩暴露在短时间内。他们以粗鲁的策略支持快速生长的一年生草药。为了优化它们的招募成功，泥滩物种的种子在波动的温度、充足的光照和有氧环境下发芽得更好，这表明存在植物生长和发育的最佳（非淹水）条件。在这里，我们假设之前将泥滩种子暴露于缺氧（淹水）环境会干扰发芽过程，并在有氧条件恢复后导致发芽更加旺盛。为了验证这一假设，五种泥滩物种的种子在四种（14/6、22/14、22/22 和 30/22°C）温度条件下在有氧和缺氧环境中孵化，反映了不同（季节性）下降时的条件可能导致。所有物种都对四种温度状况做出了积极反应；然而，适中的 22/14 和 22/22°C 温度对于种子发芽的高百分比和速率（速度）是最佳的。由于四种物种的种子完全在有氧条件下发芽，因此它们从缺氧条件转移到有氧条件。种子事先暴露于低氧环境促进了种子发芽的高百分比、速率和同步化。水生油菜,马齿苋和番荔枝种子与在严格的有氧条件下孵化相比。然而，先前暴露于缺氧环境会导致非休眠种子的二次休眠金丝桃但打破了休眠千屈菜否则需要冷分层来克服生理休眠的种子。所有具有狭窄生态位（严格发生在泥滩栖息地）的物种都对先前暴露于缺氧环境表现出积极的反应。相比之下，腐殖质具有广泛生态位（从泥滩到潮湿的沙质草原）的地区表现出负面反应。我们得出结论，一旦好氧环境恢复，缺氧环境可能会强烈影响种子发芽行为。最显着的效果是加速发芽过程，因此，生命周期支持在短暂的栖息地生存。