Hydroponic production of fireweed for biomass and phytochemicals

Abstract Fireweed (Chamerion angustifolium (L.) Holub.) is utilized worldwide in traditional medicine, due to its high levels of phenolic compounds that possess bioactive properties with a wide range of therapeutic effects on human health. However, there is little work on the direct production of fireweed for these beneficial phytochemicals. To examine the effects of nutrient availability on fireweed biomass production and metabolomic profile, fireweed plants were grown in a hydroponic greenhouse system with varying concentrations of Hoagland’s nutrient solution. As the concentration of the nutrient solution increased, shoot dry mass increased, and root:shoot ratio decreased. Variation in untargeted metabolomic profiles were detected in leaf, stem, and root tissues of hydroponically produced fireweed in response to nutrient level. Several metabolic features were identified, most notably the therapeutic compounds oenothein B and miquelianin. Relative abundances of oenothein B and miquelianin were largely unaffected by nutrient treatments, while several other phytochemicals increased in abundance as nutrient content decreased. This work demonstrates the potentiality of hydroponically cultivated fireweed to supply raw material for phytochemical demand, but the effects of mineral nutrient amendment must first be reconciled with biomass production.