Extracts of Stevia rebaudiana are rich in sweet-tasting steviol glycosides (SG), which are widely valued as natural sweeteners. This study investigated the effects of different light conditions on stevia growth and SG production across growth stages using a controlled hydroponic system. Four light conditions were introduced at a low photosynthetic photon flux density of 50 μmol·m⁻²·s⁻¹. Stevia growth was divided into four stages, and leaf weight and SG yield were analyzed. Red light resulted in the highest leaf fresh weights at 23.53 g·plant⁻¹, whereas green light resulted in the lowest at 17.15 g·plant⁻¹, marking a difference of 37.2%. However, green light performed the highest total SG content (LSG) at 190.68 mg·g⁻¹ and total SG yield (YSG) at 39.24 g·m⁻², compared to the lowest LSG under red light at 108.68 mg·g⁻¹ and YSG at 24.76 g·m⁻², derived differences of 75.45% and 58.48%, respectively. These results suggest a trade-off between vegetative growth and SG synthesis. Red light is optimal for early-stage biomass accumulation, while green light and blue light treatments during the last two stages, respectively, may enhance overall SG production. Consequently, the results offered insights into commercial stevia cultivation and the production of SG.

Stevia is a natural source of high-intensity sweeteners, collectively known as steviol glycosides (SG), which are approximately 300 times sweeter than sucrose and widely used as sugar substitutes. This study examines the impact of five different red-to-blue (R:B) light ratios on SG content and yield in hydroponic Stevia across four growth stages. Results indicate that the highest and lowest leaf dry weights were recorded in the R1B0 (R:B = 1:0) and R0B1 (R:B = 0:1) groups, at 2.88 and 1.98 g/plant, respectively, reflecting a 45.45% difference. The total SG content in dried leaves was highest in R0B1 (196.32 mg/g) and lowest in R1B0 (115.16 mg/g), with a 70.48% variation. The highest and lowest total SG yields (YSG) per square meter were observed in R0B1 (46.56 g/m²) and R50B37 (35.70 g/m²), differing by 30.42%. Stage-specific optimal YSG values were identified, with designated growth stages P1 (early vegetative growth phase), P2 (early leaf development phase), and P3 (late leaf development phase) favoring R4B1 and P4 (leaf senescence phase) favoring R0B1. These findings suggest an optimized lighting strategy for the four growth stages of hydroponic Stevia, sequentially applying R4B1, R4B1, R4B1 and R0B1 to enhance biomass accumulation and SG production at different developmental stages.