phytochemical responses of thyme to bio- and nano-fertilizer under water dificit stress

Thyme (thymus daenensis celak.), a medicinal plant rich in phenolic compounds is widely used in traditional medicine, pharmaceutical, food, cosmetic and health industries. the biosynthesis and accumulation of secondary metabolites, including phenolic compounds, which are integral to plants defense mechanisms, are influenced by environmental factors such as water deficit and nutritional stress. to investigate these effects, a three-year split-plot study was conducted using a randomized complete block design with three replications at urmia university during the 2014-2017 cropping years. the main factor was irrigation regimes at three levels: normal irrigation (once every two weeks), supplementary irrigation (once a month), and rainfed conditions (without irrigation). the sub-factor consisted of six fertilizer treatments: biofertilizer (azotobaror + phosphate-barvar 2), complete chemical fertilizer, and complete nano fertilizer, each with and without vermicompost. sampling and trait analysis were performed during the third year of planting (2016-2017). the results showed that total phenol content was significantly effect by irrigation regimes and fertilizer treatments. supplementary irrigation and rainfed conditions increased total phenol content. the combined application of nano fertilizer and vermicompost had the most significant effect on enhancing total phenol content. the interaction between irrigation regimes and fertilizer treatments indicated that low irrigation conditions increased anthocyanin content, total flavonoids, antioxidant activity, and essential oil yield while reducing total dry weight. furthermore, the combined application of nano fertilizer and vermicompost under normal and rainfed irrigation conditions, as well as the application of nano fertilizer alone under supplementary irrigation, significantly improved the thyme essential oil yield.