Dynamic changes in essential oil yield and terpenoid composition across growth stages in hemp cultivars

The essential oil of Cannabis sativa L. is a valuable product with applications in medicine, cosmetics, and biopesticides. This study evaluated the effects of growth stage on essential oil yield and composition in four hemp cultivars, including two non-native monoecious types (Fedora 17 and Fed17-2) and two native dioecious types (Fars and Yazd). Samples were collected at vegetative, flowering, and seed-setting stages, and essential oils were analyzed by GC and GC/MS. Both cultivar and growth stage significantly affected oil yield. The highest yield (0.87%) was obtained from Fed17-2, while the lowest (0.54%) was recorded in Fedora 17. Essential oil content generally increased with plant maturity. Monoterpenes ranged from 7.9–50.9% and sesquiterpenes from 46.6–86.6%. Major compounds included α-pinene, β-pinene, 1,8-cineole, E-caryophyllene, and α-humulene. Certain sesquiterpenes showed cultivar-specific patterns, particularly in native versus foreign cultivars.