Forage plants have great economic effects in soil protection and ecosystem health. Tall fescue ( Schedonorus arundinaceus Shcreb.) is one of the important forage plants that has good ability to be established and tolerate severe environmental conditions such as water and salt stresses. Low water requirements of tall fescue has made it suitable to be used as lawn. Also this plant has a symbiotic relation with entophyte fungus, Epichloe coenophiala , which provide highly tolerance to severe conditions. This relationship have a variety of effects on host plant, so present study aimed to evaluate the effect of magnetic field on the function of endophytic fungus in tall fescue. According to thye different response of plants to light wavelengths, gravity, electrical signals, and reaction to touch, studies on magnetic fields could be an importance factor. For these reasons, and with the technological advancement, use of electronic devices and increase in use of these devices that expose people to magnetic fields, we can't ignore the side-effects of magnetic field and its biological functions. Two clones of tall fescue, called 75B+ and 75C+ were used in this experiment which are maintained in the collection of forage plants at research farm of Isfahan University of Technology. Treatments in these research consisted of plant material infected with endophytic fungi and three magnetic field intensity of 500, 1700 and 2000 millitesla. Therefore, six populations with two control plants, tomato and lettuce, were planted in a completely randomized design with 3 replications. Results showed that high magnetic field up to 2000 millitesla had not significant effect on seed germination percentage and elimination of symbiotic endophytic fungus from seedlings. However, results showed that in high magnetic field,endophyte density, and growth rate of seedling, as well as root and stem length decreased. In comparison with control plants, tomato and lettuce, seeds of tall fescue are highly resistant to magnetic fields, and seemingly fungal endophytes are not affected by the magnetic field. Keywords: Tall fescue, Endophytic fungi, Symbiotic, Magnetic field, Free radicals, Penetrability, oxidation.
