Evaluating the Effect of Integrated Nutrition on Quantitative Yield and Essential Oil Percentage of Lemon Balm (Melissa officinalis)

An important requirement of agronomic planning is to evaluate different plant nutrition systems in order to achieve high yield and quality, especially in medicinal plants. With the correct method of increasing soil fertilization and plant nutrition, it is possible to reduce the erosion and conservation of biodiversity, preserve the environment, and increase the efficiency of inputs. This research was carried out with the aim of improving the quantitative and qualitative performance of lemon balm with bio fertilizers such as mycorrhiza fungi, biophosphate fertilizer, and vermicompost.

The experiment was conducted in spring and summer of 2016 in a field covered by Agriculture Jihad of Guilan, located in Khoshkabijar District of Rasht, Iran. In this research, the experiment was conducted considering three factors: factorial contains mycorrhizal inoculation (M1 = non-inoculated and M2 = inoculated), phosphate biofertilizers (P1 = 0, P2 = 50 and P3 = 100 kg ha-1) and vermicompost (V1 = 0, V2 = 5 and V3 = 10 tons ha-1) layout based on a randomized complete block design with 18 treatments and three replications. Also, one plot was allocated to control in each replication and only chemical fertilizers (use of 90 kg ha-1 of fertilizer of urea, triple super phosphate 90 kg ha-1 and potassium sulfate 90 kg ha-1) and data obtained from control plot, mycorrhizal, phosphate biofertilizers, and vermicompost were used based on a randomized complete block.

According to the results of this experiment, the highest number of leaf yield, essential oil percentage, biological yield, essential oil yield, total chlorophyll and carotenoids in inoculation with mycorrhiza was obtained. The application of 100 kg of phosphate biofertilizers had a significant effect on all measured biofertilizers. Fertilizer treatment of 100 kg ha-1 had the best result in all measured traits. Also, the best result was obtained with the use of 10 tons of vermicompost per hectare in biological yield (4808.2 kg ha-1), essential oil (0.13%), and total chlorophyll (1.54 mg gr-1FW). There were positive and synergic interactions between factors. For example, positive interaction between inoculation of mycorrhiza and phosphate biofertilizers on leaf yield and essential oil yield, and synergic interaction between mycorrhiza and vermicompost on biological yield were obsereved.

The results of this study show that the treatment of inoculums with mycorrhiza, consumption of 100 kg of phosphate biofertilizers and 10 tons of vermicompost per hectare could provide the best situation to achieve the highest quantitative (5290 kg ha-1) and qualitative yield (0.26% essential oil) of lemon balm in a sustainable agricultural system.