University of Tehran International Journal of Horticultural Science and Technology 2322-1461 13 4 2026 10 01 Impact of Foliar Application of Fullerene Nanoparticles on the Development, Productivity, and Synthesis of Secondary Metabolites in Feverfew (Tanacetum parthenium L.) during Two Distinct Harvest Phases in a Pot Experiment 821 832 104636 10.22059/ijhst.2025.391135.1036 EN Seyede Zahra Ahmadi Ph.D, Department of Horticulture Sciences, Faculty of Agriculture, Lorestan University, Khorram abad, Iran. Journal Article 2025 02 28 Purpose: Biostimulants are compounds that enhance plant productivity by activating metabolic processes, resulting in increased growth and synthesis of secondary metabolites through the stimulation of plant defense mechanisms. This study aimed to evaluate the effects of carbon nanoparticles (fullerene) on the growth and yield of feverfew (Tanacetum parthenium L.) during two harvest periods in 2021.<br />Methodes: The research was conducted using a factorial arrangement within a completely randomized design with three replications in an open-field environment at the Faculty of Agriculture, Lorestan University.<br />Results: Results showed that treatment with fullerene nanoparticles significantly increased the fresh and dry weights of aerial parts, the number of flowers, essential oil concentration, and parthenolide content in the plants. Additionally, the harvest stage had a significant impact on morphological traits, with the first harvest stage producing the best growth characteristics.<br />Conclusions: These findings could help in developing effective strategies for enhancing secondary metabolite production in medicinal plants. https://ijhst.ut.ac.ir/article_104636_008f99ad66990813c9556476e9400e87.pdf