Salinization of coastal lands by sea-level rise means that information on the response of tropical tree species to salinity is urgently required to effectively manage coastal systems under future climatic scenarios. While salinity represents a major selective abiotic stress, little is known about the underlying mechanisms determining salinity tolerance in tropical trees. We examined salinity responses in seedlings of eight neotropical tree species from Panama, including four coastal species (Sterculia apetala, Pithecellobium ungi-cati, Terminalia cattapa, and Thespesia populnea) and four inland species (Minquartia guianensis, Apeiba membranaceae, Ochroma pyramidale, and Ormosia macrocalyx). Three-month-old seedlings of each species were subjected to increasing concentrations of 80, 120, 200, and 300 mM of either NaCl or KCl, while controls were irrigated with tap water. Overall, growth parameters such as leaf area (LA), leaf area ratio (LAR), stem height (SH), total dry mass (TDM), and relative growth rates (RGR) were reduced for all species as salinity increased, regardless of salt treatment. However, species from coastal environments outperformed inland species at high salinity. For example, seedlings of coastal species growing in 300 mM of NaCl or KCl, corresponding to ~ 50% seawater, survived and maintained LA, SH, and TDM between 50 and 90% compared with control plants. In contrast, inland species showed reductions in RGR, LA, and SH of up to 100%, at 120 mM of either salt. At the foliar level, K⁺ accumulation remained similar under NaCl and KCl treatments, and almost all species, with the exception of Minquartia from inland forests, maintained foliar Na⁺ accumulation across treatments when compared to controls. While species from coastal environments maintained foliar Cl⁻ under NaCl and KCl treatments, inland species such as Ochroma showed up 95% increase in foliar Cl⁻. Our results suggest that salinity tolerance among tropical trees is predetermined by habitat association and ultimately by the ability of species to manage toxicity associated to foliar Na⁺ and Cl⁻. While the ecological implications of sea-level rise in coastal vegetation require further examination, is foreseeable that adaptation strategies in tropical shorelines consider the use of coastal species (i.e., reforestation) as the best tool to ameliorate the impact of increased salinity.

海平面上升导致沿海土地盐碱化意味着迫切需要有关热带树木物种对盐分反应的信息，以有效管理未来气候情景下的沿海系统。尽管盐度代表主要的选择性非生物胁迫，但对于确定热带树木耐盐性的潜在机制知之甚少。我们检查了来自巴拿马的8种新热带树种的幼苗中的盐分响应，其中包括4种沿海树种（无花菊，皮氏纤毛虫，卡特彼勒终端菌和Thespesia populnea）和4种内陆种（Minquartia guianensis，Apeiba membranaceae，Ochroma pyramidale和Ormosia）大花萼）。对每种物种的三个月大的幼苗分别增加80、120、200和300 mM的NaCl或KCl浓度，同时用自来水灌溉对照组。总体而言，随着盐度的增加，所有物种的生长参数（如叶面积（LA），叶面积比（LAR），茎高（SH），总干重（TDM）和相对生长率（RGR））均降低了，无论盐处理。但是，在高盐度条件下，来自沿海环境的物种优于内陆物种。例如，与对照植物相比，生长在300 mM NaCl或KCl中的沿海物种幼苗（对应于约50％的海水）可以存活并保持LA，SH和TDM在50％至90％之间。相反，内陆两种盐中的任何一种在120 mM浓度下均显示RGR，LA和SH降低高达100％。在叶面水平上，在NaCl和KCl处理下，K ^+的积累保持相似，并且与内陆森林相比，除内陆森林的Minquartia以外，几乎所有物种在叶片上均保持了Na ^+的积累。而从沿海环境物种保持叶面氯^-下的NaCl和KCl的治疗，内陆物种如Ochroma露面在叶面氯95％的增加^-。我们的研究结果表明热带树木之间是耐盐性的栖息地的联系，并最终由物种管理相关的至叶娜毒性的能力预定⁺和Cl ^- 。尽管沿海植被的海平面上升对生态的影响需要进一步研究，但可以预见，热带海岸线的适应战略将利用沿海物种（即重新造林）作为减轻盐分增加影响的最佳工具。