The changes in growth parameters, qualities, and chemical constituents of lemon balm (Melissa officinalis L.) cultivated in three different hydroponic systems
Lemon balm (Melissa officinalis L.) is a popular herb used as an aromatic and medicinal resource as well as a herbal tea. Due to a lack of information on the hydroponic growth of lemon balm, three hydroponic systems (artificial soil bed, perlite bed, and aeroponic) that could be applied to industrial production were tested in the present study. In this context, the growth parameters, mineral contents, color traits, anti-oxidative capacities, and phenolic compounds of lemon balm were analyzed. As a result, the three types of systems assessed showed similar yields and even compared to previous studies. However, the soilless cultivation system (perlite and aeroponic) showed increased nitrate content but decreased the chlorine mineral content. In addition, they showed lowered total phenolic acid content and radical scavenging capacity, which was associated with decreased rosmarinic acid and lithospermic acid A, the major phenolic compounds in lemon balm. Conversely, the caffeic acid and methyl rosmarinate content increased by 6？8 times in soilless cultivation system compared to soil-based conditions. In conclusion, the hydroponic cultivation methods used in this study could be applied to the industrial production of lemon balm with yields and qualities consistent with traditional growth conditions. In addition, soilless hydroponic systems could be used to produce specified lemon balm rich in caffeic acid and methyl rosmarinate.