Effect of short-duration microwave treatments on flower development and secondary metabolite production in Agastache rugosa

This study investigated the effects of short-duration microwave (MW) exposure on growth, photosynthesis, antioxidant activity, and secondary metabolite accumulation in Agastache rugosa cultivated in a deep flow technique hydroponic system. Plants at 14 and 18 days after transplanting were exposed to MW radiation at 200 W for 5, 10, 15, 20, and 25 s, with untreated plants serving as the control. While most vegetative growth parameters were unaffected, MW exposure for 15–25 s significantly increased flower branch number by 9–15% and flower biomass by 9–24% compared with the control. These treatments also enhanced net photosynthetic rate (by up to 53%), chlorophyll a content (by 12%), and total phenolics (by 43–85%) compared with the control. Antioxidant enzyme activities were markedly elevated, with SOD, POD, and CAT increasing by up to 66%, 49%, and 103%, respectively. MW exposure also promoted phytochemical accumulation: total flavonoids increased by 7–11%, and key bioactive compounds such as chlorogenic acid (up to 7.3-fold), tilianin (up to 53%), and rosmarinic acid (up to 42%) were significantly enhanced. These results indicate that short MW exposures of 15–25 s act as an effective elicitation strategy to improve flower development and phytopharmaceutical quality of A. rugosa under controlled cultivation conditions. An, J. H. et al. Evaluation of phytochemicals in agastache rugosa (Fisch. & C.A.Mey.) Kuntze at different growth stages by UPLC-QTof-MS. Ind. Crops Prod. 112, 608–616 (2018). Sim, L. Y., Abd Rani , N. Z. & Husain, K. Lamiaceae: an insight on their an... [11103 chars]