Effect of Fertilizers and Superabsorbent Hydrogel on the Yield, Essential Oil Content and Composition of Lemon verbena (Lippia citriodora Kunth.) Cultivated in Iran

Abstract

Various fertilizer regimes influence the content and composition of secondary metabolites. Superabsorbent hydrogels are crosslinked hydrophilic polymers that increase soil capacity to hold water, nutrients and improve the plant’s growth and yield. The aim of this investigation was to evaluate the growth parameters and essential oil (EO) content, yield and composition of lemon verbena under sole and combined application of conventional chemical fertilizers, bio-fertilizer and superabsorbent polymer. The Gas chromatography (GC) and Gas chromatography with mass spectroscopy (GC-MS) results demonstrated that oxygenated monoterpenes as the dominant class; also geranial and neral as major constituents of lemon verbena EO. Using superabsorbent hydrogel induced the highest content of geranial and neral. According to the results, although sole application of treatments was useful, their combined use was more effective to increase dry mass and oil yield of lemon verbena. Hence, the combination of chemical fertilizers plus biofertilizer and superabsorbent hydrogel can be suggested as an integrated nutrient management with the aim of optimizing the production of biomass and EO.