Forty accessions belonging to Mentha spicata, M. piperita and M. longifolia were collected from different regions of Iran (north, center and south). Initially, the roots of the genotypes were investigated to determine the percent of mychorrhizal colonization. Essential oil content and morphological traits were measured during two years. Three genotypes from Mentha species were planted in 10×20 cm pots and placed inside LED incubators containing red, blue, red+blue, white and fluorescent lights with 300 ?mol photon m -2 s -1 intensity and the plants were compared with those grown in the field. For the next step, three genotypes were inoculated with three species of AMF including G. clarum, G. mosseae and G. etunicatum and placed inside LED incubator with two different light intensities of 150 and 300 ?mol photon m -2 s -1 . Morphological characteristics and essential oil content of plants in each condition were measured and compared. Except for three genotypes, collected accessions were naturally colonized by AMF. Mycorrhizal infection ranged from 1.4 to 71.8%. The highest shoot dry weight of plants inside incubators belonged to M. piperita species and red+blue light. G. etunicatum was the best mycorrhizal species for increasing mint dry weight and white and red+blue LED lights were the best light quality in this respect at both light intensities. Essential oil content was higher under 300 than under 150 ?mol photon m -2 s -1 light intensity and also red LED was the best light in this respect. G. mosseae increased essential oil content and Ghazvin and Hamedan genotypes were the best genotypes of mint to produce essential oil while having symbiosis with AMF. Key words : Mint, LED light, Mycorrhiza
