This study aimed to identify the optimal photoperiodic conditions for Centella asiatica, a medicinal plant known for its high-value bioactive compounds, including madecassoside and asiaticoside, in a vertical farming system. C. asiatica plants were cultivated for 4 weeks under varying photoperiods 20/4, 16/8, 12/12, and 8/16 h (light/dark) with a light intensity of 200 ± 10 µmol·m− 2·s− 1. The findings revealed that shoot fresh and dry weights, leaf length, leaf area, and leaf width were highest under 20/4, 16/8, and 12/12 h, while the number of runners peaked at 12/12 h. However, physiological disorders were observed under 20/4 and 16/8 h. Total phenol, total flavonoid, and antioxidant capacity increased linearly with photoperiod, reaching their maximum at 20/4 h and minimum at 8/16 h. Madecassoside and asiaticoside concentrations increased when the photoperiod exceeded 12/12 h, while madecassic acid and asiatic acid concentrations were higher under 8/16 h. Furthermore, light-use efficiency and energy-use efficiency, energy efficiency metrics, were highest at 12/12 h compared to other treatments. These findings indicate that the optimal photoperiod for maximizing biomass and secondary metabolite production in C. asiatica grown under 200 µmol·m− 2·s− 1 white light-emitting diodes in vertical farms is 12/12 h.
Yang et al. (Sun,) studied this question.