Soil salinity is a real challenge in nowadays crop production in many regions. Various strategies have been applied to increase plant salinity tolerance. Salicylic acid (SA) frequently has been reported to increase plant salinity tolerance; however, the comparative efficiency of soil (root) or foliar application of SA has not been well tested yet. In this study, the effects of root or leaf pretreatment, and leaf treatment with 100 mg L−1 salicylic acid were evaluated on growth characteristics of tomato seedlings (Solanum lycopersicum Mill) under salinity stress. The plants were grown 3 weeks in sand that were fed with Hoagland nutrient solution with or without 100 mM NaCl. The results showed that salinity significantly reduced tomato seedling growth and traits of plant height, leaf area, shoot fresh weight, and nutrient concentration of potassium, calcium, iron and zinc compared to control plants. However, leaf SPAD value, root fresh and dry weights, leaf concentration of sodium, proline and soluble sugars were significantly increased under 100 mM NaCl salinity compared to control plants. Application of salicylic acid particularly by foliar pretreatment increased the tomato plant growth and those traits that were reduced by NaCl salinity. Application of SA, particularly foliar pretreatment, also increased the root fresh and dry weights, leaf proline and soluble sugars concentrations as compared with salinity alone. Foliar SA pretreatment significantly increased leaf K and Fe concentrations, whereas leaf Ca was significantly increased by either root or leaf pretreatment with SA under salinity. The results indicate that the most to least effective method of SA application was leaf pretreatment, root pretreatment and leaf treatment, respectively, to recover the reduced growth parameters of tomato plant under salinity stress.

中文翻译：

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水杨酸不同施用方法对盐度下番茄幼苗生长特性的影响

在当今许多地区，土壤盐分是当今作物生产中的真正挑战。已经应用了各种策略来增加植物的盐度耐受性。水杨酸（SA）经常被报道可以提高植物对盐分的耐受性。然而，土壤（根系）或叶面施用SA的比较效率尚未得到很好的测试。在这项研究中，评估了盐胁迫下根或叶预处理以及100 mg L-1水杨酸对叶片的处理对番茄幼苗（Solanum lycopersicum Mill）生长特性的影响。使植物在装有Hoagland营养液（含或不含100 mM NaCl）的沙子中生长3周。结果表明，盐度显着降低了番茄幼苗的生长，降低了番茄的株高，叶面积，枝条鲜重和钾的养分含量，钙，铁和锌与对照植物相比。然而，与对照植物相比，在100 mM NaCl盐度下，叶片SPAD值，根鲜重和干重，钠，脯氨酸和可溶性糖的叶片浓度均显着增加。水杨酸的施用，特别是叶面预处理的施用，增加了番茄的生长速度，而NaCl盐度降低了这些性状。与单独的盐度相比，SA的应用（尤其是叶面预处理）还增加了根的鲜重和干重，叶脯氨酸和可溶性糖的浓度。叶面SA预处理显着增加了叶片K和Fe的浓度，而盐分下根系或叶片预处理都显着增加了叶片Ca的含量。