Changes in Total Phenol and Some Enzymatic and Non-Enzymatic Antioxidant Activities of Rose-scented Geranium (Pelargonium graveolens) in Response to Exogenous Ascorbic Acid and Iron Nutrition

Strong antioxidant activity of Pelargonium graveolens is well known. The question addressed in this study was whether different concentrations of exogenous ascorbic acid (AsA) and iron (Fe) were able to influence antioxidant activity and total phenol content (TPC) of geranium. Thus, three levels of Fe (0, 20 and 40 µM) and three levels of AsA (0, 1 and 2 mM) in nutrient solution were combined factorially based on a completely randomized design with six replications, and chlorophyll content, TPC and antioxidant activities of leaves were measured. The results showed that oil content, ascorbate peroxidase (APX) and catalase (CAT) activities increased in leaf samples under Fe starvation, regardless of AsA concentration. The highest peroxidase (POD) activity was observed in samples under 20 µM Fe with 1 mM AsA treatment. The highest total chlorophyll content was produced in plants treated with 40 µM Fe along with 1 m M AsA. TPC increased with increasing Fe concentration. Despite of positive effect of AsA on the pigments content, plants treated with AsA showed lower TPC under all Fe concentrations. In total, lower Fe nutrition increased oil content and reactive oxygen species (ROS) scavenging activity of geranium. AsA nutrition increased oil content while decreased total phenol and antioxidant activity in this plant.