Optimization of Cultivation Type and Temperature for the Production of Balloon Flower (Platycodongrandiflorum A. DC) Sprouts in a Plant Factory with Artificial Lighting

Abstract

The objective of this study was to determine the efficiency of balloon flower sprout’s saponin production in a plant factory with artificial lighting (PFAL). Balloon flower has been traditionally used as herbal medicine and now, it is used as a medicinal plant as well as a functional food. It is important to establish the cultivation conditions for the stable production of high-quality balloon flower. Therefore, this study aimed to investigate the effects of culture systems and temperature conditions on the growth and saponin accumulation of balloon flower sprouts in controlled environment systems. One-year balloon flower roots were cultivated in soil and soilless culture systems at different temperature conditions (20, 25, and 30 °C) for 17 days. The results showed that the shoot fresh weight and shoot dry weight of the balloon flower sprouts grown in the soilless culture system at 25 °C were significantly increased by about 1.29 and 1.58 times, respectively, as compared with those of the sprouts grown in a soil culture system. Sprouts grown in the soilless culture system at 25 °C also recorded the highest root fresh weight, whereas there was no significant difference in root dry weight among the treatments. The plant height results showed an increased trend similar to that of the shoot fresh weight and shoot dry weight of the balloon flower sprouts. The concentrations of platycodin D3 (Pd-D3), polygalcin D (Pc-D), and total saponin in the shoot parts were highest in the soilless culture system at 20 and 25 °C. The root parts of sprouts grown in the soilless culture system at 30 °C also had higher deapioplatycodin D (Dpd-D) and total saponin concentrations. Overall, these results suggest that a soilless culture system with temperature conditions at 20 and 25 °C is suitable for improving the growth and saponin concentration of balloon flower cultivated in PFALs. Ultimately, our research should be a valuable resource for future research on the production of medicinal plants such as sprouts and should provide basic information to establish methods for enhancing the growth and bioactive compounds in balloon flower.