Light intensity affects growth, photosynthesis and nutritional properties of Toona sinensis sprouts in plant factory
摘要
Light intensity is a key factor regulating plant morphogenesis, photosynthesis, and secondary metabolism in controlled environments, yet its optimal range for Toona sinensis sprouts remains unclear. This study investigated sprouts from Shaanxi and Anhui under 0–150 µmol·m⁻²·s⁻¹ illumination. Light between 50 and 150 µmol·m⁻²·s⁻¹ significantly enhanced biomass accumulation, chlorophyll synthesis, PSII efficiency, and the biosynthesis of phenolics, flavonoids, and anthocyanins. Gene expression analysis showed that key photoreceptor and flavonoid biosynthetic genes (TsCRY1-like, TsCHS-like, TsFLS, TsWD40, TsDFR-like) were highly induced at 100 µmol·m⁻²·s⁻¹, while TsCHS-like and TsANS-like were downregulated at 150 µmol·m⁻²·s⁻¹, indicating feedback regulation under excessive irradiance. OJIP fluorescence confirmed PSII saturation near 100 µmol·m⁻²·s⁻¹. Shaanxi sprouts exhibited stronger light responsiveness and higher antioxidant capacity than Anhui ones. Overall, 100 µmol·m⁻²·s⁻¹ provided the most favorable balance between photosynthetic activation, metabolic enhancement, and energy efficiency.