Lemon balm (Melissa officinalis L.) is a valuable medicinal plant native to southern Europe and western Asia. Seed germination is a crucial stage in the life cycle of plants and tends to be highly unpredictable over space and time. Successful establishment of plants largely depends on successful germination. The dramatic development of carbon nanoscience and nanotechnology in recent years has offered numerous opportunities and innovative solutions in various fields and applications. Of the carbonaceous nanomaterials, graphene has been more widely and rapidly developed compared with other materials. Graphene oxide (GO), a novel engineered nanomaterial, is widely used in various fields (e.g. biology, chemistry, medicine, exploration and environmental protection) is considered to be relatively biocompatible. Polyaniline-co-graphene oxidenanoplates(PANI/GO) were prepared by in situ chemical oxidative polymerization of aniline in the presence of GO nanoplates. The morphology of the composite is examined by scanning electron microscopy (SEM) and transition electron microscopy (TEM). In this research, the influence of different concentrations of PANI/GO (0, 100, 200, 400 and 800 mg/L) were studied on seed germination parameters including germination percentage (GP %), mean germination time (MGT), germination rate (GR), germination index (GI) and seedling vigor index (SVI) in M. officinalis L for 7 days. Results showed that significant differences in examined traits were found among the employed PANI/GO concentrations. The highest (93%) and the lowest (57%) GR were observed at 200 and 800 mg/L PANI/GO concentration, respectively. However, minimum (2.45 day) and maximum (6.24) MGT were obtained at 100 mg/L PANI/GO and control treatments, respectively. Furthermore, the highest (421.6) and the lowest (162.8) SVI were calculated at 200 and 800 mg/L of the aforesaid nanocomposite treatments. The mechanisms by which carbon nanomaterials facilitate seed germination are not fully u
