Soil salinity is a widespread stress in semi-arid forests worldwide, but how to manage nitrogen (N) nutrition to improve plant saline tolerance remains unclear. Here, the cuttings of a widely distributed poplar from central Asia, Populus russikki Jabl., were exposed to either normal or low nitrogen (LN) concentrations for two weeks in semi-controlled greenhouse, and then they were added with moderate salt solution or not for another two weeks to evaluate their physiological, biochemical, metabolites and transcriptomic profile changes. LN-pretreating alleviated the toxicity caused by the subsequent salt stress in the poplar plants, demonstrated by a significant reduction in the influx of Na⁺ and Cl^- and improvement of the K⁺/Na⁺ ratio. The other salt-stressed traits were also ameliarated, indicated by the variations of chlorophyll content, PSII photochemical activity and lipid peroxidation. Stress alleviation resulted from two different processes. First, LN pretreatment caused a significant increase of non-structural carbohydrates (NSC), allowed for an increased production of osmolytes and a higher potential fueling ion transport under subsequent salt condition, along with increased transcript levels of the cation/H⁺ ATPase. Second, LN pretreatment enhanced the transcript levels of stress signaling components and phytohormones pathway as well as antioxidant enzyme activities. The results indicate that early restrictions of N supply could enhance posterior survival under saline stress in poplar plants, which is important for plantation programs and restoration activities in semi-arid areas.

土壤盐分是全球半干旱森林中普遍存在的压力，但如何管理氮 (N) 营养以提高植物的耐盐性仍不清楚。在这里，来自中亚的广泛分布的杨树的插条，Populus russikki Jabl.，在半控制温室中暴露于正常或低浓度氮 (LN) 浓度下两周，然后添加或不添加中等盐溶液再过两周来评估他们的生理、生化、代谢物和转录组学特征的变化。LN 预处理减轻了杨树植物中随后的盐胁迫引起的毒性，这通过显着减少 Na ⁺和 Cl ^-的流入以及 K ⁺ /Na 的改善来证明⁺比率。其他盐胁迫性状也得到改善，表现为叶绿素含量、PSII 光化学活性和脂质过氧化的变化。压力缓解是由两个不同的过程引起的。首先，LN 预处理导致非结构性碳水化合物 (NSC) 的显着增加，允许在随后的盐条件下增加渗透物的产生和更高的潜在燃料离子传输，同时增加阳离子/H ^{+ 的}转录水平ATP酶。其次，LN 预处理增强了应激信号成分和植物激素途径的转录水平以及抗氧化酶活性。结果表明，早期限制氮供应可以提高杨树在盐分胁迫下的后存活率，这对半干旱地区的人工林计划和恢复活动很重要。