Floral development and phenolic compounds production in Agastache rugosa through light regulation.

Main conclusion: The regulation of photoperiod and light intensity significantly affected Agastache rugosa by enhancing growth, modifying flowering dynamics, and promoting the accumulation of key phenolic compounds. Agastache rugosa is a medicinal and aromatic plant valued for its bioactive compounds, which contribute to its application in the flavoring, perfume, and food industries. However, variability in the composition of the bioactive compounds poses challenges for its commercial utilization. Light is a key external signal that regulates plant development and flowering by activating various signaling pathways. This study investigated the effects of extended photoperiods and light intensities on flowering dynamics and phenolic compound accumulation in A. rugosa. The results demonstrated that reduced light intensity promoted vertical growth and biomass accumulation. Furthermore, extended photoperiods significantly enhanced flower productivity and accelerated floral development. Notably, under extended photoperiods with lower light intensity, flowering initiation was delayed; however, subsequent maturation progressed more rapidly, effectively compensating for the initial delay. Extended photoperiod also influenced organ-specific accumulation of phenolic compounds. While high light intensity combined with an extended photoperiod enhanced phenolic compound accumulation in vegetative tissues, lower light intensity under the same conditions led to increased flavonoid accumulation in reproductive tissues. These findings provide valuable insights into the role of light regulation in optimizing both floral productivity and bioactive compound accumulation in A. rugosa, offering potential strategies for its controlled cultivation and industrial application.