The Study on the Effect of Spraying with Different Concentrations of Vermicompost Extract (Vermiwash) on the Morphological Traits, Yield and Percentage of Essential oil of Lemon balm (Melissa officinalis L.)

To investigate the effect of spraying with different concentrations of Vermiwash solution on the morphological traits، percentage and yield of essential oil of lemon balm (Melissa officinalis L.)، this experiment was conducted as Randomized Complete Block Design (RCBD) with four replications in experimental field of Agricultural Faculty of Ferdowsi University of Mashhad (FUM). The treatments were included 4 different concentrations of Vermiwash solution (0، 3000. 6000 and 12000 ppm). At the flowering stage، morphological characteristics include of plant height، number of nod and internodes length، as well as total fresh weight، leaf area، dry weight of plant، yield and percentage of essential oil were determined. Results showed that there was a significant difference between different treatments in terms of plant height، number of node، internodes length، leaf area، and dry weight of plant and essential oil yield. The highest height (84. 91 cm)، number of node (23. 20)، leaf area (8853. 52 cm2) and plant dry weight (174. 31 g) related to vermiwash concentration of 3000 ppm and the longest internodes (7. 02 cm) and essential oil yield (6 g/m2) related to concentration of 1200 ppm. In conclusion، application of 3000 ppm vermiwash was the superior among the all studied treatments that confirmed activity of plant growth regulators in low concentration of vermiwash and availability of nutrient in the solution.