Effect of Magnetic Field Treatments on Seed Germination of Melissa officinalis L.

Abstract

Melissa officinalis L., commonly known as lemon balm, is a perennial herb belonging to Lamiaceae family. It has therapeutic properties, such as sedative, carminative, antispasmodic, anti-viral, wound healing, digestive, diuretic, diaphoretic, antiseptic and anti-thyroid. Lemon balm has been used for the treatment of headache, indigestion, colic, nervousness, cardiac problems, depression, rheumatism, indigestion, hypersensitivities, anxiety and depression traditionally. Beneficial effects of lemon balm are ascribed to the phenolic compounds such as rosmarinic acid, tannins and flavonoids. Studies showed that magnetic field applications in agriculture can be used to improve the quality and quantity of the product. Positive effects of the stationary magnetic field on the plant seed germination have been recorded with some plant species. In this study, effects of magnetic field on M. officinalis seeds were investigated. Seeds were sterilized in 0.1 % HgCl2 for 10 min and 70 % Ethanol for 1-2 min. After surface sterilization of the seeds, they were placed in petri dishes containing Murashige and Skoog's medium with sucrose and agar. Neodymium block magnets (100 X 50 X 5 mm) were used to create magnetic fields (50 mT and 100 mT). Ten seeds were placed in each petri plates and 10 petri plates were used for each treatment. Petri dishes containing surface sterilized seeds were placed in 3 different conditions [without magnetic field application (control) and magnetic field applications (low-50 mT and high-100 mT)] and the germination (radicle protrusion) was assessed. Seeds were exposed to magnetic fields for 1, 3, 6, 12, 24, 48, 72, 144 and 240 hours. The number of germinated seeds was recorded for 20 days. Best seed germination was obtained with 100 mT magnetic field application for 1 hour (52 %). Seed germination rate was rather low (28 %) without magnetic field application (control). In consistent with 100 mT magnetic field application, 1 hour exposure to 50 mT magnetic field gave better germination rate (36 %) than control. The lowest seed germination was observed with 240 hours exposure to both magnetic fields (27 % for 100 mT and 16 % for 50 mT). Magnetic field applications also decreased the seed germination time. Although seed germination was observed in 11. day with control, it was obtained in 7. day with both magnetic field applications. Magnetic field application enhanced the percentage of germinated seed and shortened the period of seed germination in M. officinalis.