Development of a solar smart farm model for the production of temperate crops in the tropics: a case study on Panax ginseng

Introduction – High cooling-energy requirements and operational costs constrain the controlled-environment production of temperate crops in tropical regions. To overcome these limitations, a Solar Smart Farm (SSF) system was developed as an energy-assisted controlled-environment model for Panax ginseng production in tropical climates. Methods – The performance of the SSF system was evaluated in terms of renewable energy contribution, cultivation performance, and phytochemical quality. Growth characteristics and commercial ginseng sprout yield were assessed at 4, 6, 8, and 10 weeks after transplanting (WAT). Total saponin content was determined by ultraviolet-visible spectrophotometry, while major ginsenosides in 6-WAT sprouts were quantified using high-performance liquid chromatography. Results – The integrated semi-transparent solar panels addressed approximately 48% to 63% of the high energy demands of SSF systems. The SSF system, covering an area of 25 square meters, is capable of growing up to 13, 650 ginseng seedlings per six-week cycle, with a commercial ginseng sprout rate ranging from 71.52% to 88.91%, depending on seedling quality. Peak growth, reaching a 166% increase in fresh weight by 6 weeks after transplanting (WAT), coincided with the highest saponin content. High-performance liquid chromatography analysis of sprouts at 6 WAT confirmed the presence of key ginsenosides (Rb1, Rd, Re) and a notably high concentration of Rg1 (11.61 mg • g−1). The concentrations of these ginsenosides were comparable to, or even surpassed, those documented in the tested 6-year-old ginseng roots. Specifically, the Rd content in the sprout shoots achieved a 17-fold enhancement over that quantified in the mature roots. Conclusion – These findings demonstrate the technical potential of the SSF system as a controlled-environment agriculture model for cultivating high-value temperate crops such as P. ginseng sprouts in thermally challenging tropical environments.