Supplementary irrigation along with mycorrhizal symbiosis is one of the effective methods to increase quality and quantity of performance. To evaluate mycorrhizal symbiosis of rainfed Rye (Secale cereal L.) plants, a 2-year factorial experiment was conducted based on randomized complete block design with three replications at West Azarbaijan Agricultural and Natural Resources Research Center during 2014 and 2015. Treatments were rain interrupted (30 May, 13 June and 27 June), mycorrhizal symbiosis (non-inoculated plants and inoculation with Glomus intraradices) and irrigation (rainfed and one time supplementary irrigation).Mycorrhizal symbiosis under supplementary irrigation significantly increased the forage phosphorus, calcium and ash, and grain potassium and protein more than rainfed condition. The mycorrhizal symbiosis enhanced the forage and grain quality. However, the yield enhancement under supplemental irrigation was better than rainfed condition. The highest grain protein concentration (18/43 %) belonged to mycorrhizal plants exposed to rainfall continuing 20 May. The highest grain yield in the second year under supplementary irrigation of about 1412.96 kg/ha, which have precipitation until 17 June. In general, rainfed rye forage and grain quality were improved with one time supplemental irrigation, and mycorrhizal relationship affedcted the grain quality and yield regardless rainfall interruption. In mycorrhizal rye plants, rainfall continuing until 17 June with supplemental irrigation was increased the grain yield (23 %) more than that rainfed condition in early rain interrupted
