Beijing Forestry University, Beijing 100091, China.
Ying Yong Sheng Tai Xue Bao. 2024 Feb;35(2):431-438. doi: 10.13287/j.1001-9332.202402.001.
We investigated the effects of exogenous melatonin on the osmotic regulation and antioxidant capacity of 4-year-old seedlings under salt stress. There were three treatments, with low (50 mmol·L), medium (100 mmol·L), and high (200 mmol·L) NaCl stress. Leaves were sprayed and the soil was watered with melatonin solution (0, 0.02, 0.1, 0.5 mmol·L). The results showed that saline stress significantly inhibited the osmoregulation and antioxidant capacities of seedlings. Application of exogenous melatonin at appropriate concentrations (0.02, 0.1 mmol·L) under salt stress could promote plant growth, reduce the rate of electrolyte leakage, decrease the content of flavonoids and malonic dialdehyde, and enhance peroxidase and superoxide dismutase activities in leaves. High concentration (0.5 mmol·L) of exogenous melatonin would aggravate the oxidative and osmotic stresses. The 0.02 and 0.1 mmol·L exogenous melatonin alleviated osmotic stress and oxidative stress in seedlings under salt stress, while the 0.02 mmol·L exogenous melatonin treatment had the best effect on NaCl stress alleviation. Ground diameter, branch width, branch length, electrolyte leakage rate, superoxide dismutase activity, and flavonoids content could be used as the key indices for rapid identification of the degree of salt stress in seedlings.
我们研究了外源褪黑素对盐胁迫下 4 年生幼苗渗透调节和抗氧化能力的影响。设低（50mmol·L）、中（100mmol·L）、高（200mmol·L）3 种 NaCl 胁迫处理，叶面喷施和灌根施用褪黑素溶液（0、0.02、0.1、0.5mmol·L）。结果表明，盐胁迫显著抑制了幼苗的渗透调节和抗氧化能力。在盐胁迫下，适宜浓度（0.02、0.1mmol·L）的外源褪黑素的应用可促进植物生长，降低电解质渗透率，减少类黄酮和丙二醛的含量，并增强叶片中过氧化物酶和超氧化物歧化酶的活性。高浓度（0.5mmol·L）的外源褪黑素会加重氧化胁迫和渗透胁迫。0.02 和 0.1mmol·L 的外源褪黑素缓解了盐胁迫下幼苗的渗透胁迫和氧化胁迫，而 0.02mmol·L 的外源褪黑素处理对缓解 NaCl 胁迫的效果最好。地径、分枝宽度、分枝长度、电解质渗透率、超氧化物歧化酶活性和类黄酮含量可作为快速识别 幼苗盐胁迫程度的关键指标。
