Melatonin (MEL) is an antioxidant molecule, present throughout plant kingdom, animals, and microbes. It is a well-known free radical scavenger and modulates growth and development in plants against various abiotic and biotic stresses. The present study was done to investigate the role of MEL as a foliar spray on the morphological, physiological, and biochemical parameters in Brassica juncea cv. Varuna. Five different doses (10, 20, 30, 40, or 50 μM) of MEL were applied as foliar spray to the leaf of plant at 25 days after sowing (DAS) and continued up to 30 DAS once in a day. The plants were sampled at 30, 45, and 60 DAS to assess various parameters. The present results indicate that most of the parameters, i.e., growth, photosynthetic, nutrients, and enzyme activities increased in a concentration dependent manner. MEL application reduced the accumulation of reactive oxygen species (ROS) by enhancing the antioxidant enzyme activities. Microscopic examinations further revealed a significant increase in the size of the stomatal aperture in the presence of MEL. Out of the various concentrations tested, 40 μM of MEL proved best and can be used for further studies.

中文翻译：

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褪黑激素调节光合作用、氧化还原状态和元素组成以促进芥菜的生长——一种剂量依赖性效应

褪黑激素 (MEL) 是一种抗氧化分子，存在于植物界、动物和微生物中。它是一种众所周知的自由基清除剂，可调节植物的生长和发育以抵抗各种非生物和生物胁迫。本研究旨在研究 MEL 作为叶面喷雾剂对芥菜 cv. 形态、生理和生化参数的作用。瓦鲁纳。在播种后 25 天 (DAS)，将五种不同剂量（10、20、30、40 或 50 μM）的 MEL 作为叶面喷洒施用于植物的叶子上，并持续至每天 30 DAS。在 30、45 和 60 DAS 时对植物进行采样以评估各种参数。目前的结果表明，大多数参数，即生长、光合作用、营养物质和酶活性以浓度依赖性方式增加。MEL 应用通过增强抗氧化酶活性减少了活性氧 (ROS) 的积累。显微镜检查进一步揭示了在 MEL 存在下气孔孔径的大小显着增加。在测试的各种浓度中，40 μM 的 MEL 被证明是最好的，可用于进一步研究。