Studies have shown that the application of arbuscular mycorrhizal (AM) fungi or exogenous melatonin (MT) can alleviate drought stress and improve plant growth, but the additive effects of both treatments on plants grown under drought stress are largely unknown. In this study, we conducted a pot experiment to investigate the effects of AM inoculation ( Funneliformis mosseae BGC XJ01) and/or MT application on tobacco ( Nicotiana tabacum L. cv. Yuyan No. 6) seedling growth, photosynthetic and chlorophyll fluorescence parameters, antioxidant enzymatic activity, osmotic adjustment substance accumulation, and nutrient uptake under three water conditions (75–80%, 50–55%, and 30–35% of the maximum moisture retention capacity). The results show that applying either the AM inoculant or MT alone significantly increased tobacco seedling growth and decreased the negative effects of drought stress. Furthermore, AM inoculation alone promoted root function (root biomass, root/shoot ratio, root system architecture), facilitated the capture and conversion of solar energy (photosynthetic rate, Φ PSII ), and increased nutrient uptake more effectively than MT. In contrast, exogenous MT application alone was more effective at increasing peroxidase and catalase activity and decreasing H 2 O 2 and MDA accumulation, which in turn enhanced the adaptation of seedlings to drought stress by improving their antioxidant capacity and reducing oxidative damage. Nevertheless, applying exogenous MT significantly enhanced the AM colonization rate under AM inoculation conditions but had no obvious effect on AM colonization under noninoculated conditions. The combined application of AM and MT had an additive effect and produced the largest increases in tobacco seedling growth, photosynthetic ability, antioxidant enzymatic activity, and N, P, and K uptake and the largest decreases in H 2 O 2 and MDA contents of all the treatments. The results suggest that AM inoculation in combination with exogenous MT application may render plants more productive and more tolerant of drought stress.

中文翻译：

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丛枝菌根真菌与外源褪黑素联合应用减轻干旱胁迫，促进烟草幼苗生长

研究表明，施用丛枝菌根 (AM) 真菌或外源褪黑激素 (MT) 可以缓解干旱胁迫，促进植物生长，但两种处理对干旱胁迫下生长的植物的累加作用尚不清楚。在本研究中，我们进行了盆栽试验，研究了 AM 接种（Funneliformis mosseae BGC XJ01）和/或 MT 施用对烟草（Nicotiana tabacum L. cv. Yuyan No. 6）幼苗生长、光合和叶绿素荧光参数的影响，三种水分条件下的抗氧化酶活性、渗透调节物质积累和养分吸收（最大保湿能力的75-80%、50-55%和30-35%）。结果表明，单独施用 AM 接种剂或 MT 显着增加了烟草幼苗的生长并降低了干旱胁迫的负面影响。此外，单独接种 AM 可促进根功能（根生物量、根/茎比、根系结构），促进太阳能的捕获和转化（光合速率，Φ PSII），并且比 MT 更有效地增加养分吸收。相比之下，单独施用外源MT在增加过氧化物酶和过氧化氢酶活性以及减少H 2 O 2 和MDA积累方面更有效，这反过来通过提高幼苗的抗氧化能力和减少氧化损伤来增强幼苗对干旱胁迫的适应。尽管如此，外源MT在AM接种条件下显着提高AM定植率，但对非接种条件下AM定植率无明显影响。AM和MT的联合施用具有相加作用，使烟草幼苗生长、光合能力、抗氧化酶活性和N、P、K吸收量增加最大，H 2 O 2 和MDA含量降低幅度最大。治疗。结果表明，AM 接种与外源 MT 应用相结合可以使植物更具生产力和对干旱胁迫的耐受性。P、K 的吸收以及所有处理的 H 2 O 2 和 MDA 含量下降幅度最大。结果表明，AM 接种与外源 MT 应用相结合可以使植物更具生产力和对干旱胁迫的耐受性。P、K 的吸收以及所有处理的 H 2 O 2 和 MDA 含量下降幅度最大。结果表明，AM 接种与外源 MT 应用相结合可以使植物更具生产力和对干旱胁迫的耐受性。