Forest ecosystems are frequently exposed to abiotic stress, which adversely affects their growth, resistance and survival. For silver fir (Abies alba), the physiological and biochemical responses to water and salt stress have not been extensively studied. Responses of one-year-old seedlings to a 30-day water stress (withholding irrigation) or salt stress (100, 200 and 300 mM NaCl) treatments were analysed by determining stress-induced changes in growth parameters and different biochemical markers: accumulation of ions, different osmolytes and malondialdehyde (MDA, an oxidative stress biomarker), in the seedlings, and activation of enzymatic and non-enzymatic antioxidant systems. Both salt and water stress caused growth inhibition. The results obtained indicated that the most relevant responses to drought are based on the accumulation of soluble carbohydrates as osmolytes/osmoprotectants. Responses to high salinity, on the other hand, include the active transport of Na⁺, Cl⁻ and Ca²⁺ to the needles, the maintenance of relatively high K⁺/Na⁺ ratios and the accumulation of proline and soluble sugars for osmotic balance. Interestingly, relatively high Na⁺ concentrations were measured in the needles of A. alba seedlings at low external salinity, suggesting that Na⁺ can contribute to osmotic adjustment as a ‘cheap’ osmoticum, and its accumulation may represent a constitutive mechanism of defence against stress. These responses appear to be efficient enough to avoid the generation of high levels of oxidative stress, in agreement with the small increase in MDA contents and the relatively weak activation of the tested antioxidant systems.

中文翻译：

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银杉（Abies alba Mill。）幼苗对水分亏缺和盐胁迫的响应

森林生态系统经常遭受非生物胁迫，这不利于其生长，抵抗和生存。对于银杉（冷杉冷杉），对水分和盐胁迫的生理和生化反应尚未进行广泛研究。通过确定胁迫引起的生长参数变化和不同的生化指标变化，分析了一年龄幼苗对30天水分胁迫（不灌溉）或盐胁迫（100、200和300 mM NaCl）处理的响应。离子，不同的渗透液和丙二醛（MDA，一种氧化应激生物标记），并激活酶促和非酶促抗氧化剂系统。盐和水分胁迫均引起生长抑制。获得的结果表明，与干旱最相关的响应是基于可溶性碳水化合物作为渗透压/渗透压保护剂的积累。另一方面，对高盐度的反应包括Na ⁺的主动转运，氯^-和Ca ²⁺到针上，相对高K的维护⁺ /钠⁺比值和脯氨酸的积累和渗透平衡的可溶性糖。有趣的是，在低盐度条件下，在晨曲幼苗的针中测得的Na ⁺浓度相对较高，表明Na ⁺可以作为“廉价”的渗透压促进渗透调节，并且其积累可能代表防御压力的本构机制。这些反应似乎足够有效，可以避免产生高水平的氧化应激，这与MDA含量的小幅增加和被测抗氧化剂系统的活化相对较弱相符。