Marchin Renée M, Ossola Alessandro, Leishman Michelle R, Ellsworth David S
Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.
Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia.
Front Plant Sci. 2020 Jan 21;10:1715. doi: 10.3389/fpls.2019.01715. eCollection 2019.
Drought is expected to increase in frequency and severity in many regions in the future, so it is important to improve our understanding of how drought affects plant functional traits and ecological interactions. Imposing experimental water deficits is key to gaining this understanding, but has been hindered by logistic difficulties in maintaining consistently low water availability for plants. Here, we describe a simple method for applying soil water deficits to potted plants in glasshouse experiments. We modified an existing method (the "Snow and Tingey system") in order to apply a gradual, moderate water deficit to 50 plant species of different life forms (grasses, vines, shrubs, trees). The method requires less maintenance and manual handling compared to other water deficit methods, so it can be used for extended periods of time and is relatively inexpensive to implement. With only a few modifications, it is possible to easily establish and maintain soil water deficits of differing intensity and duration, as well as to incorporate interacting stress factors. We tested this method by measuring physiological responses to an applied water deficit in a subset of 11 tree/shrub species with a wide range of drought tolerances and water-use strategies. For this subgroup of species, stomatal conductance was 2-17 times lower in droughted plants than controls, although only half of the species (5 out of 11) experienced midday leaf water potentials that exceeded their turgor loss (i.e., wilting) point. Leaf temperatures were up to 8°C higher in droughted plants than controls, indicating that droughted plants are at greater risk of thermal damage, relative to unstressed plants. The largest leaf temperature differences (between droughted and well-watered plants) were in species with high rates of water loss. Rapid osmotic adjustment was observed in leaves of five species when drought stress was combined with an experimental heatwave. These results highlight the potential value of further ecological and physiological experiments utilizing this simple water deficit method to study plant responses to drought stress.
预计未来许多地区干旱的频率和强度将会增加，因此加深我们对干旱如何影响植物功能性状和生态相互作用的理解非常重要。施加实验性水分亏缺是获得这种理解的关键，但一直受到为植物持续维持低水分可利用性方面后勤困难的阻碍。在此，我们描述一种在温室实验中对盆栽植物施加土壤水分亏缺的简单方法。我们对现有的一种方法（“斯诺和廷吉系统”）进行了改进，以便对50种不同生活型（草本植物、藤本植物、灌木、乔木）的植物施加逐渐的、适度的水分亏缺。与其他水分亏缺方法相比，该方法所需的维护和人工操作较少，因此可长时间使用且实施成本相对较低。只需进行一些修改，就能够轻松建立和维持不同强度和持续时间的土壤水分亏缺，还能纳入相互作用的胁迫因素。我们通过测量11种具有广泛耐旱性和水分利用策略的乔木/灌木物种对施加的水分亏缺的生理反应来测试该方法。对于这一物种亚组，干旱处理的植物气孔导度比对照低2至17倍，尽管只有一半的物种（11种中的5种）中午叶片水势超过其膨压丧失（即萎蔫）点。干旱处理的植物叶片温度比对照高8°C，这表明相对于未受胁迫的植物，干旱处理的植物遭受热损伤的风险更大。最大的叶片温度差异（干旱处理和充分浇水的植物之间）出现在失水率高的物种中。当干旱胁迫与实验性热浪相结合时，在5个物种的叶片中观察到了快速渗透调节。这些结果凸显了利用这种简单的水分亏缺方法进行进一步的生态和生理实验以研究植物对干旱胁迫反应的潜在价值。
