Optimization of LED-based phototreatments for enhancing antioxidant potential and marketable traits in microgreens

Light spectrum, intensity, and photoperiod are pivotal determinants of microgreen growth and nutritional quality, yet species-specific optimization remains underexplored. This study applied response surface methodology (RSM) to assess the interactive effects of LED spectral composition (white, blue–red, red–far-red, blue–red–far-red), light intensity (100–300 μmol m⁻² s⁻¹), and photoperiod (12–20 h) on antioxidant potential of radish and mung bean microgreens. In radish, the blue -red–far-red spectrum at 300 μmol m⁻² s⁻¹ and 20 h photoperiod (L4 (BRFr) -300-20) maximized antioxidant activity (50.52 ± 1.45% DPPH) and total phenolic content (355.77 ± 8.42 mg GAE/100 g), showing 51% and 59% increases over control. In mung bean, maximum antioxidant activity (81.27 ± 1.22%) was achieved under blue-red–far-red spectra at 100 µmol m⁻²s⁻¹ and a 20 h photoperiod (L4 (BRFr) -100-20), with TPC (205.78 ± 2.30 mg GAE/100 g) comparable to control. Overall, radish exhibited greater relative gains in both antioxidant activity and TPC under optimized light regimes compared with mung bean, indicating a higher responsiveness to spectral manipulation. Red–far-red light promoted elongation and fresh biomass in both species, whereas blue-red–far-red spectra at high intensity enhanced dry matter accumulation. The optimized treatments also reduced oxidative stress and stimulated stress-adaptive metabolism, supporting cellular stability under extended lighting. Improved pigment content under optimized lighting in mung bean and reduced nitrate accumulation (up to 35%) in both species indicate enhanced product quality and consumer safety. This research provides actionable, species-specific lighting recommendations that enable efficient production of nutritionally superior, antioxidant-rich microgreens within commercial controlled-environment agriculture systems.