The method of biological production of nanoparticles has recently attracted a lot of attention because of its features such as compatibility with the environment, simplicity, and low cost. Zinc oxide nanoparticles (ZnONPs) have recently been used in many industries, including medicinal plant production, optics, electronics, packaged foods, and medicine. This study inves- tigated the effects of ZnONP spraying on the chemical compounds of Tanacetum parthenium. Foliar spraying of ZnONPs was performed at 1000, 1500, and 2000 ppm, and essential oil (EO) extraction and analysis were performed by randomized complete block design. The results showed that the total compounds of EO increased from 96.47 in the control to 100% by spraying of ZnONPs (2000 ppm). Furthermore, ZnONPs in all concentrations improved the amount of camphor and trans- chrysanthenyl acetate as the main compounds; however, the highest effects were related to 1500 ppm ZnONP treatment. ZnONP treatments changed the EO-grouped compounds. Therefore, oxygenated monoterpenes, as the biggest one, increased in all treatments compared with the control, and the highest increase, 83.55%, was seen in the 1500 ppm treatment. Finally, the amount of EO increased significantly by ZnONP treatment compared with the control, but the highest increase (0.91%) was obtained at 1000 ppm. Overall, foliar spraying of ZnONPs at all levels improved the quality and quantity of feverfew EO.
