2019 ASHS Annual Conference

The aim of this study was to investigate optimum light conditions for increasing growth and phytochemicals contents of Korean mint (Agastache rugosa) grown under a hydroponics culture system in a controlled environment room. First, 100, 200, and 400 µmol·m^-2·s^-1 were tested with florescence lamps for finding suitable photosynthetic photon flux density (PPFD) for 3 weeks experiment period (EX-1). Several photoperiods of 12/12, 16/8h, 20/4h, 24/0 hours (day and night) were investigated for growing and accumulation of rosmarinic acid and tilianin of Korean mint (EX-2). Finally, combination of PPFD-photoperiod, 133-24, 160-20, 200-16, 266-12, and 400-8 hours, under the same daily light integral (DLI), with florescence lamps were treated for how affected the growth and accumulation of rosmarinic acid and tilianin in an environment-controlled room for 4 weeks (EX-3). The air temperature and relative humidity of the room was maintained at 22±1°C and 18±1°C and 65±10% and 75±10% during day and night. After 4 weeks of sowing, they were transplanted in an NFT culture system installed in the room. Shoot fresh weight of Korean mint increased proportionally with increasing PPFDs, showing significant difference. However, rosmarinic acid and tilianin contents per unit g dry weight were the greatest in 200 µmol·m^-2·s^-1 than those of 100 and 400 µmol·m^-2·s^-1 condition. The stem lengths increased proportionally with the photoperiod and the fresh weights was not significantly different at 16, 20, and 24 hours treatments, showing the highest value at 24 hours. Rosmarinic acid and tilianin contents per unit g dry weight at 12 hours photoperiod showed the highest value with significant difference, but least at 24 hours. However, those values per unit a plant dry weight showed the smallest value in 12 hours photoperiod, because of its less biomass. Also 16 hours with 200 PPFD was showed the highest values to produce two phytochemiclas which can be used for health supplements. Under the same DLI condition, the longer the day length, the greater the fresh weight, but the PPFD increased and the functional substance content increased except for the 400 PPFD condition. PPFDs of 200 to 266 µmol·m^-2·s^-1 could be suitable for increasing rosmarinic acid and tiliain accumulated Korean mint with 16 to 20 hours photoperiods without growth inhibition in an indoor farming system.