Biochemical composition and biological activity of radish sprouts grown in near-infrared radiation

Background The quality of light strongly influences plant growth and the accumulation of bioactive compounds, yet the effects of near-infrared radiation beyond the far-red region remain poorly understood. This study investigated whether near-infrared radiation at 850 nm and 940 nm could modulate the morphology, nutritional value, phytochemical composition, and biological activity of radish sprouts grown without visible light. Results Both near-infrared treatments induced significant changes in radish sprout composition compared with darkness, although neither wavelength restored chlorophyll synthesis or prevented etiolation. Sprouts grown under 940 nm radiation showed the highest protein content, while maintaining a stable amino acid profile and high protein quality. In contrast, 850 nm radiation promoted the accumulation of ascorbic acid, anthocyanins, and several carotenoids, resulting in more intense red pigmentation. Both wavelengths increased the concentrations of lutein, violaxanthin, and selected sinapic acid derivatives relative to dark-grown sprouts, indicating stimulation of secondary metabolism. Dry matter, fiber content and amino acid composition remained unaffected by the treatments. Acetone-based carotenoid extracts obtained from sprouts cultivated under 940 nm radiation more effectively reduced lipopolysaccharide-induced interleukin-6 production in Raw 264.7 macrophages than extracts from the other treatments. Conclusions Near-infrared radiation beyond the far-red range modifies plant metabolism independently of photosynthesis and represents an effective elicitor of bioactive compound accumulation in radish sprouts. The two wavelengths produced distinct responses: 940 nm primarily enhanced protein accumulation together with pro-inflammatory interleukin decrease, whereas 850 nm preferentially stimulated the synthesis of antioxidant phytochemicals, including carotenoids, anthocyanins, and ascorbic acid. These findings demonstrate that wavelength-specific near-infrared radiation can be used to tailor the nutritional and functional quality of sprouts and highlight a potential application in controlled-environment agriculture and sustainable functional food production.