Investigation of the Effects of Chemical, Organic and Compost Fertilizers on Chemical Composition of Essential Oil of Pelargonium graveolens

Introduction: One of the important factors in the succeeding the medicinal plant cultivation is the use of appropriate fertilizers. Plants grown with appropriate fertilizers have more secondary metabolites than those that grown in the usual system. On the other hand, there is increasing concern about soil interrelated environmental problems such as desertification, soil degradation, loss of fertility and erosion. So, the use of suitable fertilizer for plant growth is very important. Geranium (Pelargonium graveolens) oil is widely used as a floral substitute of the rose scent, due to its smell very similar to rose, being therefore one of the most valuable natural materials for the cosmetic and perfumery industries. Geranium oil is obtained from steam distillation of the flowers or green foliage of Pelargonium graveolens or some of its hybrids. Geranium oil is sometimes listed on the label of supplements promoted for athletic performance, weight loss, and body building. Sometimes it is used for nerve pain (neuropathy), depression, diarrhea and various skin conditions or to help with healing. Also, geranium oil is likely safe when taken by mouth in food amounts. Analyses of phytochemical profile of geranium oil included the major constituents such as citronellol, citronellyl formate, geraniol and isomenthone. The aim of this study was to evaluate the compounds of geranium essential oil in treatment of three types of fertilizers including organic, chemical and compost fertilizer. Materials and Methods: In order to investigate the effects of organic, chemical and compost fertilizers on chemical composition of essential oil of geranium, an experiment was conducted at Barij research farm, Kashan, Iran, in 2015 as factorial layout based on a randomized complete block design with three replications. Treatments included; organic fertilizer at one level (3 tons/ha), chemical fertilizer as urea at two levels (75 and 100 kg/ha), compost fertilizer as plant debris at two levels (15 and 20 tons/ha) and control (no fertilizer). The aerial parts of the treated geranium were collected during stage of flowering in October, and their essential oils were obtained from Clevenger apparatus, and after dehydration were analyzed by GC device. The GC analysis was carried out using Varian 3800 GC, equipped with a CP-Sil 8 fused silica capillary column (60 m × 0.32 mm i.d., 0.25 µm f.t.); carrier gas, Helium; flow rate 1.0 ml/min; split ratio, 1:50 and using a flame ionization detector. The column temperature was programmed at 50 °C heated to 250 °C at a rate of 3.0 °C/min, then kept constant at 250 °C for 20 min; injector temperature, 230 °C; detector temperature, 250 °C. Also, plant height, number of branches per plant, average fresh weight of the plant, maximum fresh weight of the plant and plant yield were measured. Data analysis was done by SPSS Statistic 17.0. Results and Discussion: The results showed that treatment with different fertilizers had no significant effect on essential oil percentage. In the cultivation of aromatic herbs, despite the percentage of essential oil, the type and composition of the essential chemical composition is also important. So, the chemical compounds of essential oils obtained from different treatments were studied. Citronellol (44.5%-56.6%), citronellyl formate (12.2%-18.3%), geraniol (2.2%-7.6%), and isomenthone (1.9%-6.1%) were found as four major components in essential oil of geranium. However, it’s found that the amount of citronellol (51.94%) reach to the highest level in the essential oil obtained from germanium treated with compost fertilizer at level of 15 tons/ha. However, other treatments had no significant effect on other compounds of essential oil. Several studies indicate that the use of compost on land may soil parameters and improve several plant and which would make compost an interesting option for soil restoration purposes, as well as take advantage of its fertilizer properties. Other potential benefits of compost application are enhanced nutrient availability for plants, improved biological activity, and the suppression of soil borne diseases. Moreover, many authors have reported higher yields with compost application and better quality of the harvested crops. Also, no significant differences among geranium for plant height, number of branches per plant, average fresh weight of the plant, maximum fresh weight of the plant and plant percentage were observed. Conclusion: The results point to the beneficial effects of a compost fertilizer at level of 15 tons/ha as alternative nutrition systems on the growth characteristics. So, in addition to reducing costs, can be achieved high quality essential oil.