Polyphenol Content And Essential Oil Composition Of Sweet Basil Cultured In A Plant Factory With Light-Emitting Diodes

This study was conducted to determine the most suitable light-emitting diodes (LEDs) for enhancing the growth characteristics, polyphenolic compounds, and essential oils in sweet basil (Ocimum basilicum L.) cultured in a plant factory. There were four LED combinations using three colors [Blue (B):Red (R):White (W) ratio = 0:1:9, 0:1:12, 0:5:5, and 2:3:5). The environmental conditions in the plant factory were maintained at 22.5 +/- 2.5 degrees C and 80 +/- 5% relative humidity. Sweet basil plants were grown in the plant factory at 3 weeks after sowing. The four combinations of LED light sources exerted a significant effect on total fresh weight (FW), shoot FW, and root FW but no effect on plant height and number of leaves. The B0:R5:W5 treatment resulted in the largest increases in both total FW and shoot FW. Both plant height and number of leaves did not change significantly with LED treatments but showed the best average growth using B0:R5:W5. The three major polyphenols were identified as rosmarinic acid, chicoric acid, and caffeic acid. Rosmarinic acid content accounted for the highest percentage of the polyphenols and was followed by chicoric and caffeic acids. The highest contents of rosmarinic and chicoric acids were achieved with B2:R3 :W5, but no significant difference in caffeic acid was found among the four LED conditions. Furthermore, B2 :R3 :W5 resulted in the highest yield of essential oil extracted from 50 g freeze-dried leaves of sweet basil, followed by B0:R5:W5, B0:R1:R12, and B0:R1:W9. Methyl-cinnamate content accounted for the highest percentage of the essential oils, followed by linalool, estragole, and eugenol, regardless of the LEDs. In conclusion, the B2:R3 :W5 light treatment was the most suitable one for increasing polyphenols and the yield of essential oils in sweet basil.