Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana 70506 USA.
Am J Bot. 2002 Nov;89(11):1847-51. doi: 10.3732/ajb.89.11.1847.
Saltwater intrusion into wetland ecosystems has destroyed or damaged many native plant populations. Iris hexagona is a salt-sensitive species that exhibits intraspecific variation in salinity tolerance. To investigate the effect of salinity on flowering, we exposed I. hexagona collected from natural populations to salt treatments in a common garden. Experimental salinity additions strongly delayed flowering phenology, but the effect was not apparent until the second year, when less than 4 g/L NaCl delayed flowering up to 3 d. In the field, soil salinity and flowering phenology varied substantially within I. hexagona populations. Iris flowers are receptive to pollinators for 2 d or less, therefore a 3-d delay could affect outcrossing dynamics, and ultimately, the evolutionary ecology of iris populations. Salinity also had a carryover effect; prior salinity exposure delayed flowering in irises that had been replanted in freshwater conditions for 6 mo. This is an important result because it suggests that episodic stress (such as tropical storms) can influence performance well after the stress has disappeared. Our research further underscores the importance of long-term studies because a 1-yr experiment would have failed to reveal the strong effects of salinity that emerged in the second year.
海水入侵湿地生态系统已经破坏或损害了许多本地植物种群。六角果因其对盐度敏感，表现出种内耐盐性变异。为了研究盐度对开花的影响，我们将从自然种群中采集的六角果暴露在一个普通花园的盐处理中。实验性盐度增加强烈延迟了开花物候，但直到第二年才明显，当时不到 4 g/L NaCl 将花期延迟了 3 天。在野外，土壤盐度和开花物候在六角果种群内有很大差异。鸢尾花对传粉者的接受期为 2 天或更短，因此 3 天的延迟可能会影响异交动态，并最终影响鸢尾种群的进化生态学。盐度也有滞后效应；先前的盐度暴露会延迟在淡水条件下重新种植 6 个月的鸢尾花的开花时间。这是一个重要的结果，因为它表明，间歇性胁迫（如热带风暴）在胁迫消失后很长一段时间内仍会影响性能。我们的研究进一步强调了长期研究的重要性，因为为期 1 年的实验本应无法揭示第二年出现的强烈盐度效应。
