Fruits of sweet pepper ( L.) are among the most consumed fresh fruits, however, their production can be affected by aphids, which feed on the amino acids in the leaves. Mg in leaves plays a crucial role in the reallocation of amino acids from source organs (leaves) to sink organs (fruits). We hypothesize that foliar application of Mg can reduce free amino acid concentration in leaves by promoting their transfer to sink fruits, thereby compromising aphid colonization by reducing their nutritional basis. To test this, a two-factorial experiment was conducted with sweet pepper subjected to aphid infestation with and without leaf MgSO application. The concentration of amino acids, sugars, organic acids and mineral nutrients was analysed in the leaves, leaf phloem sap and fruits. Mgapplication decreased the concentrations of amino acids and sugars that are key for aphid nutrition in both the leaf and phloem sap and increased the size and number fruits, indicating an increased sink strength in response to Mg. This response was accompanied by a reduced number of aphids on the entire plant. In results, the sugar and amino acid concentration in the phloem got less attractive for the aphids. We conclude that Mg worsens the nutritional situation for aphids by facilitating the reallocation of metabolites to form fruits.

中文翻译：

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通过 MgSO4 促进氨基酸和糖的重新分配，无需使用杀虫剂即可减少甜椒 (Capsicum annuum L.) 上的桃蚜


甜椒 (L.) 的果实是消费量最大的新鲜水果之一，但其产量可能会受到以叶子中的氨基酸为食的蚜虫的影响。叶子中的镁在氨基酸从源器官（叶子）到库器官（果实）的重新分配中起着至关重要的作用。我们假设叶面施用镁可以通过促进游离氨基酸转移到库果实来降低叶片中的游离氨基酸浓度，从而通过减少其营养基础来损害蚜虫的定殖。为了测试这一点，对遭受蚜虫侵染的甜椒进行了双因素实验，并在叶子上施用和不施用 MgSO4。分析了叶子、叶韧皮部汁液和果实中氨基酸、糖、有机酸和矿物质营养素的浓度。施用镁降低了叶子和韧皮部汁液中对蚜虫营养至关重要的氨基酸和糖的浓度，并增加了果实的大小和数量，表明对镁的反应库强度增加。这种反应伴随着整个植物上蚜虫数量的减少。结果，韧皮部中的糖和氨基酸浓度对蚜虫的吸引力降低。我们得出的结论是，镁通过促进代谢物重新分配以形成果实而使蚜虫的营养状况恶化。