The interaction of selenium (Se) and melatonin in plants is unclear. The aim of this study was to investigate the effects of Se root application on melatonin synthesis in sweet cherry. Cultivar ‘Russia No.8’ was treated with Se⁶⁺ (sodium selenate) or Se²⁻ (selenomethionine). Parameters of plant antioxidant levels, growth parameters, and the synthesis enzyme activities and precursor contents of melatonin were measured. Results showed that the plant benefited more from Se⁶⁺ than Se²⁻ and were not exposed to Se stress by four low doses of Se⁶⁺ (0, 0.2, 0.4, and 0.6 mg kg⁻¹) treatments for 40 days. The trends of tryptophan hydroxylase (TPH), tryptamine-5-hydroxylas, and arylalkylamine N-acetyltransferase activities were similar, while tryptophan decarboxylase (TDC), serotonin-N-acetyltransferase (SNAT), caffeic acid-O-methyltransferase, and N-acetyl-5-hydroxytryptamine-O-methyltransferase (ASMT) activities were different in leaves and roots following different Se⁶⁺ treatments. Tryptophan and 5-hydorxy tryptophan contents were not influenced by the Se⁶⁺ dose. Tryptamine was not detected in leaves or roots, but the serotonin content was increased by Se⁶⁺ treatment. The leaf content of N-acetyl-5-tryptophan was not influenced, but its synthesis was significantly induced in roots as the Se dose increased. Melatonin synthesis in leaves and roots was increased only following treatment with 96 mg Se⁶⁺. The leaf Se and melatonin content showed no significant linear relationship in the ‘Russia No.8’ cultivar. Treatment with Se²⁻ increased the enzyme levels of TDC, TPH, SNAT, and ASMT more significantly than Se⁶⁺. Overall, lower doses of Se⁶⁺ did not significantly induce melatonin synthesis, but the relationship between melatonin and Se²⁻ merits further attention.

植物中硒 (Se) 和褪黑激素的相互作用尚不清楚。本研究的目的是研究硒根施用对甜樱桃褪黑激素合成的影响。用Se ⁶⁺（硒酸钠）或Se ^2-（硒代蛋氨酸）处理栽培品种'Russia No.8' 。测量了植物抗氧化水平、生长参数以及合成酶活性和褪黑激素前体含量的参数。结果表明，植物从 Se ^{6+ 中}获益多于 Se ^2-，并且没有暴露于四种低剂量 Se ⁶⁺（^{0、0.2、0.4}和 0.6 mg kg ^-1) 治疗 40 天。色氨酸羟化酶 (TPH)、色胺-5-羟化酶和芳烷基胺 N-乙酰转移酶活性的趋势相似，而色氨酸脱羧酶 (TDC)、血清素-N-乙酰转移酶 (SNAT)、咖啡酸-O-甲基转移酶和 N-不同Se ⁶⁺处理后，叶和根中乙酰5-羟色胺-O-甲基转移酶(ASMT) 活性不同。色氨酸和 5-羟基色氨酸含量不受 Se ⁶⁺剂量的影响。在叶或根中未检测到色胺，但 Se ⁶⁺增加了血清素含量治疗。N-乙酰-5-色氨酸的叶含量不受影响，但随着硒剂量的增加，其在根中的合成显着诱导。仅在用 96 mg Se ⁶⁺处理后，叶和根中的褪黑激素合成增加。'俄罗斯8号'品种叶片硒和褪黑激素含量无显着线性关系。用Se ^2-处理比Se ⁶⁺更显着地增加TDC、TPH、SNAT 和ASMT 的酶水平。总体而言，较低剂量的Se ⁶⁺不会显着诱导褪黑激素合成，但褪黑激素与Se ^2-之间的关系值得进一步关注。