غلامرضا عبدی

Peppermint is one of the most important and commonly used medicinal and aromatic plants worldwide. Present experiment was conducted to evaluate the essential oil content and quantitative changes of the main components of peppermint plants at different stages of crop growth. Greenhouse pots with peppermint Plants (30, 60 and 90 days after transplanting) were subjected to three different field capacity (FC) irrigation conditions, i.e. no stress, mild stress (60± 5% FC) and moderate stress (40± 5% FC) for one month. Essential oil composition and accumulation in peppermint was different‏ by plant growth stage alterations. The proportions of some monoterpene such as menthofuran, limonene, and pulegone decreased as plant matured, while those of menthol, cineole, and neomenthol increased. Both mild and moderate water stresses changed the essential oil content. Essential oil content of plants subjected to mild stress increased while moderate water stress treatment caused a significant reduction in essential oil content in different plant growth stage. Moderate stress reduced the essential oil percentage and changed the essential oil profile. Menthone content decreased and menthofuran content increased under moderate stress. Also, relative proportions of sesquiterpenes increased with water stress.