Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
Plant Sci. 2012 Nov;196:77-84. doi: 10.1016/j.plantsci.2012.08.007. Epub 2012 Aug 14.
The ability of an invasive species to establish and spread to new areas may depend on its ability to tolerate a broad range of environmental conditions. Due to climate change, increasing occurrences of extreme events such as droughts are expected in the Mediterranean region and invasive species may expand if they cope with water stress. Limited information is available on the responses of Acacia longifolia, one of the most aggressive plant species in Portuguese coastal sand dune ecosystems, to prolonged water stress. In this study, we exposed A. longifolia plants from two distinct populations, one from the wet (northern) and another from the dry (southern) climate regions of Portugal, to drought conditions, and monitored morphological, physiological and biochemical responses. One-month-old seedlings were submitted to three different water treatments which involved watering twice a week, every 7 days and every 10 days, respectively, for three months, under controlled conditions. Overall, the progressive drought stress significantly affected most of the growth parameters considered, except the root:shoot ratio. Water stress also increased the uptake of ions (Ca²⁺, Mg²⁺, K⁺ and Na⁺) and N concentration. On the contrary, the C/N ratio decreased under water stress conditions. Isotopic analysis did not reveal significant differences in δ¹³C with water treatments but the same pattern was not observed in δ¹⁵N values. Compared with the wet climate population, the dry climate population showed somewhat differing responses to water stress, indicating a genetic difference between populations. These results provide insights into limitations and opportunities for establishment of A. longifolia in a drought-prone scenario.
入侵物种在新地区建立和传播的能力可能取决于其耐受广泛环境条件的能力。由于气候变化，预计在地中海地区极端事件（如干旱）的发生频率将会增加，如果入侵物种能够应对水资源压力，它们可能会扩张。关于葡萄牙沿海沙丘生态系统中最具侵略性的植物物种之一——长叶相思（ Acacia longifolia ）对长时间水胁迫的响应，我们所掌握的信息有限。在这项研究中，我们将来自葡萄牙两个不同气候区（北部湿润区和南部干旱区）的长叶相思植株暴露在干旱条件下，并监测了它们的形态、生理和生化响应。一个月大的幼苗分别接受三种不同的水分处理，即每周浇水两次、每 7 天浇水一次和每 10 天浇水一次，持续三个月，在受控条件下进行。总体而言，渐进的干旱胁迫显著影响了大多数生长参数，除了根冠比。水分胁迫还增加了离子（Ca²⁺、Mg²⁺、K⁺和 Na⁺）和 N 浓度的吸收。相反，在水分胁迫条件下 C/N 比降低。同位素分析并未显示 δ¹³C 与水分处理之间有显著差异，但 δ¹⁵N 值的情况并非如此。与湿润气候种群相比，干旱气候种群对水分胁迫的反应有些不同，表明种群之间存在遗传差异。这些结果为了解长叶相思在干旱易发地区的建立所面临的限制和机遇提供了新的认识。
