Effects of light intensity and temperature on growth and secondary metabolite production of Centella asiatica in vertical farms

The functional compounds in Centella asiatica L., namely four types of triterpene glycosides (asiatic acid, asiaticoside, madecassic acid, and madecassoside), are highly valuable in various industries. As potent antioxidants, there is a demand to explore conditions that enhance their production and functional compound content for their application in diverse environmental conditions. This study investigates the cultivation of C. asiatica in vertical farms, seeking conditions that yield higher concentrations of functional compounds through two light intensities (100 ± 10 and 300 ± 10 µmol m⁻² s⁻¹) and three temperature levels (control: 24/20°C, High I: 30/26°C, and High II: 36/32°C). As the temperature increased, the content of functional substances (total phenolic content (TPC), total flavonoid content (TFC)) and antioxidant activities (measured by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays), as well as most growth parameters including fresh and dry weights of both above-ground and below-ground parts, increased. However, a decrease in all parameters was observed at High II (36/32°C), with all photochemical chlorophyll fluorescence parameters exhibiting lower values. This study identified a trend in which proline content increased as temperature decreased from the optimal growth temperature (30/26°C) for C. asiatica. Among the two light intensities used in the experiment, PFD 100 enhanced biomass production, whereas PFD 300 increased the content of beneficial secondary metabolites. Higher temperature conditions (specifically High I: 30/26°C) are necessary to enhance the yield of C. asiatica, while functional compounds can be improved by increasing the light intensity to PFD 300. These findings suggest that for cultivating C. asiatica on vertical farms, treatment with High I (30/26°C)_PFD 300 provides the optimal balance between biomass production and triterpene glycoside content, making it the most efficient cultivation condition for commercial applications.