Variation in salinity tolerance and water use strategies in an introduced woody halophyte (Tamarix spp.)

1. The form and function of terrestrial plants is largely governed by the availability of water, with plants in water limited environments expressing traits minimizing water loss and tissue damage during drought. Areas with high salinity are analogous to those with low water availability, even where water is abundant. We evaluated variation in salinity tolerance and water use strategies in an introduced halophytic shrub, Tamarix spp by measuring gas exchange rates, biomass accumulation, and turgor loss points. We hypothesized that salinity tolerance is not uniformly expressed, with high salinity ecotypes expressing more conservative water use traits that maximize hydraulic safety over high conductance rates. 2. We studied two populations of Tamarix spp. along the lower Colorado River where groundwater salinity differed by nearly six-fold. Cuttings collected from the sites were grown in a greenhouse with five salinity levels from 0 to 32 parts per thousand (ppt), imposing increasing w...1. 陆生植物的形态与功能在很大程度上受水分可获得性调控：水分受限生境中的植物会演化出相应性状，以降低干旱期的水分流失与组织损伤风险。高盐度区域与低水分可获得性生境具有相似的胁迫效应，即便当地水资源充足亦是如此。本研究以引入种盐生灌木柽柳属（Tamarix spp.）为研究对象，通过测定气体交换速率、生物量积累及膨压损失点，评估其盐胁迫耐受性与水分利用策略的变异特征。我们提出如下假说：盐胁迫耐受性并非均匀表达，高盐生境的生态型会表现出更为保守的水分利用性状，即优先保障水力安全而非高传导速率。 2. 本研究选取科罗拉多河下游的两个柽柳属（Tamarix spp.）种群作为研究材料，两地地下水盐度差异近6倍。从各采样点采集的插条被种植于温室中，设置0至32千分比（parts per thousand, ppt）共5个盐度梯度，以施加逐步递增的盐胁迫……