Application of nanomaterial graphene oxide on biochemical traits of Milk thistle (Silybum marianum L.) under salinity stress

In recent years, application of engineered nanomaterials, in particular carbon-based nanostructures, has been initiated in agriculture. To better understand the effects of nanomaterials on plants, four concentrations of graphene oxide (0, 0.01, 0.05, 0.1%) in soil was studied on growth and biochemical traits of Milk thistle under four saline stress (0, 4, 8,12 dS/m) conditions in greenhouse. A completely randomized block design with a factorial treatment arrangement was employed with three replications. The result showed under both saline and control (non-saline) conditions, the maximum plant height (3.7% and 20% in control and saline conditions, respectively), total biomass (17% and 8.2% in control and saline conditions, respectively), and chlorophyll content (8% and 5% in control and saline conditions, respectively), were achieved for plants with graphene oxide (GO) application. By increasing the salinity level, plants treated with 0.01% concentration of graphene oxide produced the highest total biomass (518 mg) under 12 dS/m salinity levels. Also, maximum quantum efficiency of PSII, performance index, and membrane stability index decreased due to salinity stress. Proline and soluble carbohydrates noticeably increased by saline water treatments. Graphene oxide alleviated salt stress-induced damage through increasing plant growth, plant height, chlorophyll content, photosystem efficiency, performance index, membrane stability index, proline and soluble carbohydrate content. Also graphene oxide increased cell water potential through enhancing the net concentration of solutes in plant cells. Graphene nanomaterials could ameliorate the salt stress in Milk thistle plant. Graphene oxide application could be commercially and economically beneficial for Milk thistle production under control and saline conditions.