This study evaluated the effects of foliar spraying melatonin (MT) on the growth of salt-stressed rice. Seedlings were treated with 50 and 100 mM of NaCl and different concentrations of MT (25, 50, 100, 200, 300, and 400 μM) for 14 days. Different concentrations of MT could promote plant growth significantly under salt stress, particularly at concentrations of 200, 300, and 400 μM. A concentration of 200 μM MT was considered as optimal and used in a subsequent experiment on biomass, water content, antioxidation, mineral nutrition, salt absorption, and distribution of salt-stressed rice seedlings. Results showed that MT’s promoting effect on plant growth under salt stress was evident with time, particularly under high salt stress. MT improved the activities of antioxidant enzymes, reduced membrane lipid peroxidation, alleviated cell injury in plant leaves, and increased N content and Si accumulation in the leaves and roots under salt stress, particularly under high salinity. This compound also inhibited Na uptake and upward transport, but it promoted or maintained the uptake and upward transport of K and Ca in salt-stressed rice. Thus, MT improved the ion homeostasis of K/Na and Ca/Na in plants, particularly in the leaves. Foliar spraying of MT alleviated salt stress on rice by promoting nutrient accumulation or translocation, improving ion homeostasis, which is evident in the leaves, and consequently enhancing its salt resistance. The antioxidative improvement caused by MT might also be related to the improved ion homeostasis.

本研究评估了叶面喷洒褪黑激素 (MT) 对盐胁迫水稻生长的影响。幼苗用 50 和 100 mM NaCl 和不同浓度的 MT（25、50、100、200、300 和 400 μM）处理 14 天。在盐胁迫下，不同浓度的 MT 可以显着促进植物生长，特别是在 200、300 和 400 μM 的浓度下。200 μM MT 的浓度被认为是最佳的，并用于随后的生物量、水分、抗氧化、矿物质营养、盐吸收和盐胁迫水稻幼苗分布的实验。结果表明，MT对盐胁迫下植物生长的促进作用随着时间的推移而明显，尤其是在高盐胁迫下。MT提高了抗氧化酶的活性，减少了膜脂过氧化，减轻植物叶片细胞损伤，增加盐胁迫下，特别是高盐胁迫下叶片和根部的氮含量和硅积累。该化合物也抑制了钠离子的吸收和向上转运，但它促进或维持了盐胁迫水稻对钾和钙的吸收和向上转运。因此，MT 改善了植物中 K/Na 和 Ca/Na 的离子稳态，特别是在叶子中。叶面喷施 MT 通过促进养分积累或转移，改善叶片中明显的离子稳态，从而增强其抗盐性，从而减轻了水稻的盐胁迫。MT 引起的抗氧化改善也可能与改善的离子稳态有关。该化合物也抑制了钠离子的吸收和向上转运，但它促进或维持了盐胁迫水稻对钾和钙的吸收和向上转运。因此，MT 改善了植物中 K/Na 和 Ca/Na 的离子稳态，特别是在叶子中。叶面喷施 MT 通过促进养分积累或转移，改善叶片中明显的离子稳态，从而增强其抗盐性，从而减轻了水稻的盐胁迫。MT 引起的抗氧化改善也可能与改善的离子稳态有关。该化合物也抑制了钠离子的吸收和向上转运，但它促进或维持了盐胁迫水稻对钾和钙的吸收和向上转运。因此，MT 改善了植物中 K/Na 和 Ca/Na 的离子稳态，特别是在叶子中。叶面喷施 MT 通过促进养分积累或转移，改善叶片中明显的离子稳态，从而增强其抗盐性，从而减轻了水稻的盐胁迫。MT 引起的抗氧化改善也可能与改善的离子稳态有关。叶面喷施 MT 通过促进养分积累或转移，改善叶片中明显的离子稳态，从而增强其抗盐性，从而减轻了水稻的盐胁迫。MT 引起的抗氧化改善也可能与改善的离子稳态有关。叶面喷施 MT 通过促进养分积累或转移，改善叶片中明显的离子稳态，从而增强其抗盐性，从而减轻了水稻的盐胁迫。MT 引起的抗氧化改善也可能与改善的离子稳态有关。