Light Regime Engineering in the Tank Cultivation of Ulva fasciata for Yield Enhancement and Functional Food Applications

The present study aims to optimize light regime engineering for Ulva fasciata biomass cultivation through the maintenance of culture conditions, as light serves as a crucial factor for increasing yield potential. The experimental light intensities (15–159 μmol m 2 s) were subjected to linear (LLRE) and exponential (ELRE) light‐feeding strategies combined with three light‐feeding rates ( k l and k e ), including 1, 2, and 3, every 6 h light increase rate, two stocking densities, that is, a lower popular density (10 no. flask −1 , LPD) and a higher population density (100 no. flask −1 , HPD). The weight‐based daily growth rate (16% ± 0.5% and 15.35% ± 3.13% day −1 ), length‐based extension growth rate (9.40 ± 0.73 and 6.70 ± 1.29 cm month −1 ), breadth‐based extension rate (9.40 ± 0.73 and 3.81 ± 0.60 cm month −1 ), total chlorophyll pigment content (11.99 ± 0.61 and 11.26 ± 0.07 mg g −1 FW), carbohydrate content (33.57% ± 0.24% and 29.96% ± 0.24%), protein content (27.72% ± 0.38% and 31.01% ± 0.31%), lutein content (0.83 ± 0.01 and 0.19 ± 0.14 mg g −1 ww) and survival rates (10% ± 0% and 9% ± 0.89% day −1 ) were greater in L‐III and E‐III under LPD than in the other tested combinations. This standardized LRE distinctly revealed that increased k l and k e values accelerate growth, survival rates, pigments and nutritional profiles, suggesting that irradiance is a crucial factor for the photosynthetic performance of U. fasciata . However, a negative correlation was observed between lipids and the highest exposure to light rates, whereas for LLRE, the lipid max (0.03%) was observed for L‐I:10 and L‐I:100, and for ELRE, the lipid max (0.03%) was found to be highest for the E‐I:10, E‐I:100, and E‐II:10 combinations. Hence, U. fasciata has potential for use in pharmacological sectors because of its antihyperlipidemic and antidiabetic activities.