Effect of balanced fertilization, biofertilizers and superabsorbent polymer on the yield and chemical compound characteristics of lemon verbena (Lippia citriodora H. B. et K.)

Lippia citriodora H. B. et K. is a valuable medicinal plant whose extract, as its main chemical composition, has active components such as Geranial and Limonene widely used in pharmaceutical, food, cosmetic and health industries. In medicinal plants, balanced fertilization using chemical and biological inputs has great effect on yield and phytochemicals related to yield production. This study was conducted in the greenhouse of Tarbiat Modares University. In this experiment, seven treatments were performed in a completely randomized block design with three replications. The aim of this study was to investigate the effects of balanced fertilization and super-absorbent polymer on the chemical components and yield of Lippia citriodora. After planting and harvesting operations and growth performance measurements, essential oil was dehydrated by distilled water method using Clevenger and Sodium sulfate. Using gas chromatography and gas chromatography connected to spectrum, 15 compounds were determined in essential oil, consisting more than 90% of essential oil components. Results showed that there was a significant difference among treatments (p< 0.01). The lowest and highest fresh yield were related to control (6410 kg.ha-1) and balanced fertilization + bio-fertilizer + super-absorbent polymer (15435 kg. ha-1) treatments, respectively. The lowest and highest dry leaf yield were obtained in control (702 kg.ha-1) and balanced fertilization + bio-fertilizer + super-absorbent polymer (1503 kg. ha-1) treatments, respectively. The lowest and highest essential oil content was achieved in control (7.4 kg.ha-1) and balanced fertilization + bio-fertilizer + super-absorbent polymer (20.5 kg.ha-1) treatments, respectively. In terms of overall essential oil components, the minimum and maximum contents of Neral and Geranial were obtained in control and balanced fertilization treatments with 41.2% and 52.27%, respectively.