We investigated the effects of exogenous melatonin on the osmotic regulation and antioxidant capacity of 4-year-old Ginkgo biloba seedlings under salt stress. There were three treatments, with low (50 mmol·L-1), medium (100 mmol·L-1), and high (200 mmol·L-1) NaCl stress. Leaves were sprayed and the soil was watered with melatonin solution (0, 0.02, 0.1, 0.5 mmol·L-1). The results showed that saline stress significantly inhibited the osmoregulation and antioxidant capacities of G. biloba seedlings. Application of exogenous melatonin at appropriate concentrations (0.02, 0.1 mmol·L-1) 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-1) of exogenous melatonin would aggravate the oxidative and osmotic stresses. The 0.02 and 0.1 mmol·L-1 exogenous melatonin alleviated osmotic stress and oxidative stress in G. biloba seedlings under salt stress, while the 0.02 mmol·L-1 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 G. biloba seedlings.
以4年生银杏幼苗为材料,进行不同浓度盐胁迫(50、100、200 mmol·L-1)处理,叶片喷施和土壤浇灌外源褪黑素溶液(0、0.02、0.1、0.5 mmol·L-1),研究外源褪黑素对盐胁迫下银杏幼苗渗透调节和抗氧化能力的影响。结果表明: 盐胁迫显著抑制银杏幼苗渗透调节和抗氧化能力,而在盐胁迫下施用适宜浓度(0.02、0.1 mmol·L-1)的外源褪黑素能够促进植株生长,降低电解质外渗率,减少黄酮和丙二醛含量,促进叶片中过氧化物酶、超氧化物歧化酶(SOD)活性的提高,但高浓度(0.5 mmol·L-1)外源褪黑素会进一步加剧氧化胁迫和渗透胁迫。0.02和0.1 mmol·L-1外源褪黑素处理缓解了盐胁迫下银杏幼苗的渗透胁迫和氧化胁迫,且0.02 mmol·L-1外源褪黑素处理对盐胁迫缓解效果最佳。地径、枝条宽度、枝条长度、电解质外渗率、SOD活性和黄酮含量可作为快速鉴定银杏受盐胁迫程度的关键指标。.
Keywords: antioxidant system; exogenous melatonin; ginkgo; osmotic system; salt stress.