Abstract Salinity reduces plant biomass and may lead to death when severe. To cope with the negative effects of this stress, plant species present specific physiological or biochemical responses. In this work, we hypothesized that spraying salt-stressed thyme leaves with K+ and Ca2+ could mitigate the negative effects of salinity on plant growth and metabolism. To test this hypothesis, we grew thyme plants under salinity stress for two and four weeks before applying foliar sprays. Also, to test the effect of stress relief, treated plants were allowed two weeks of recovery after four weeks of salt stress. In general, after two and four weeks of salinity stress, the leaf fresh weight of thyme plants was reduced by 31 and 43%, respectively. Salinity also decreased the relative water content, water, and osmotic potentials and led to ion imbalances and nutrient deficiencies. Salinity altered concentration of some essential oils, but leaf antioxidant contents remained fairly stable, except for a significant increase for plants under NaCl + KCl two weeks after treatment. Our results indicated that stressed plants accumulated significantly more soluble sugars and amino acids in comparison with the control. Foliar sprays with KCl and CaCl2 reversed the negative effects of salinity on plant biomass and induced the accumulations of compatible solutes. Moreover, concentrations of some essential oils and gallic acid increased in sprayed plants, but these effects were dependent on the type and duration of the treatment. Overall, spraying leaves with K+ and Ca2+ was able to mitigate salinity stress in Thymus vulgaris even during the recovery period.

中文翻译：

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叶面肥对百里香生长及盐分胁迫生化反应的影响

摘要 盐度降低植物生物量，严重时可能导致死亡。为了应对这种压力的负面影响，植物物种表现出特定的生理或生化反应。在这项工作中，我们假设用 K+ 和 Ca2+ 喷洒盐胁迫的百里香叶可以减轻盐分对植物生长和代谢的负面影响。为了验证这一假设，我们在施用叶面喷雾之前在盐胁迫下种植百里香植物 2 周和 4 周。此外，为了测试缓解压力的效果，在 4 周的盐胁迫后，允许处理过的植物恢复两周。一般而言，经过 2 周和 4 周的盐胁迫，百里香植株的叶片鲜重分别降低了 31% 和 43%。盐度也降低了相对含水量，水，和渗透势，并导致离子失衡和营养缺乏。盐度改变了一些精油的浓度，但叶片抗氧化剂含量保持相当稳定，除了在 NaCl + KCl 处理两周后植物显着增加。我们的结果表明，与对照相比，受胁迫的植物积累了显着更多的可溶性糖和氨基酸。含 KCl 和 CaCl2 的叶面喷洒逆转了盐度对植物生物量的负面影响，并诱导了相容溶质的积累。此外，喷洒植物中一些精油和没食子酸的浓度增加，但这些影响取决于处理的类型和持续时间。总体而言，即使在恢复期，用 K+ 和 Ca2+ 喷洒叶子也能够减轻百里香的盐分胁迫。