Purple lettuce (Lactuca sativa L. cv. Zhongshu Purple Lettuce) was chosen as the trial material, and LED intelligent light control consoles were used as the light sources. The purpose was to increase the yield and quality of purple lettuce while lowering its nitrate level. By adding various ratios of NO₃⁻-N and NH₄⁺-N to the nutrient solution and 20 µmol m⁻² s⁻¹ UV-A based on white, red, and blue light (130, 120, 30 µmol m⁻² s⁻¹), the effects of different NO₃⁻-N/NH₄⁺-N ratios (NO₃⁻-N, NO₃⁻-N/NH₄⁺-N = 3/1, NH₄⁺-N) and UV-A interaction on yield, quality, photosynthetic characteristics, anthocyanins, and nitrogen assimilation of purple lettuce were studied. In order to produce purple lettuce hydroponically under controlled environmental conditions, a theoretical foundation and technological specifications were developed, taking into account an appropriate UV-A dose and NO₃⁻-N/NH₄⁺-N ratio. Results demonstrate that adding a 20 µmol m⁻² s⁻¹ UV-A, and a NO₃⁻-N/NH₄⁺-N treatment of 3/1, significantly reduced the nitrate level while increasing the growth, photosynthetic rate, chlorophyll, carotenoid, and anthocyanin content of purple lettuce. The purple leaf lettuce leaves have an enhanced capacity to absorb nitrogen. Furthermore, plants have an acceleration of nitrogen metabolism, which raises the concentration of free amino acids and soluble proteins and promotes biomass synthesis. Thus, based on the NO₃⁻-N/NH₄⁺-N (3/1) treatment, adding 20 µmol m⁻² s⁻¹ UV-A will be helpful in boosting purple lettuce production and decreasing its nitrate content.

Anthocyanins are widely common natural antioxidants and represent an important economic feature in vegetables, but the potential response of UVA–blue co-irradiation on the anthocyanin biosynthesis of pak choi is not clear. Here, we investigated the effects of the supplement of four doses of UVA to blue light on growth, metabolites and the anthocyanin biosynthesis of two cultivars of pak choi. The results revealed that supplementing UVA light to blue light positively affected the growth of the pak choi and elevated the soluble protein content and antioxidant capacity. Especially, when compared with a monochromatic blue light, the anthocyanin synthesis was enhanced with an increase in UVA light strength, which reached a peak value at the strength of 10 μmol·m⁻²·s⁻¹. Further study revealed that the UVA–blue co-irradiation enhanced the transcription of partial light-induced and anthocyanin structural genes. The intraspecific difference in the expression patterns of MYB1 and PAP1 were observed in these two tested cultivars. MYB1 was significantly up-regulated in red-leaf pak choi, but down-regulated in purple-leaf pak choi. On the contrary, PAP1 was significantly up-regulated in purple-leaf pak choi, but down-regulated in red-leaf pak choi. To sum up, this study established an efficient pre-harvest lighting strategy to elevate the economic value of pak choi.

Rapeseed (Brassica napus L.) is a globally important oilseed crop; however, its ‘double-low’ cultivars exhibit substantially reduced glucosinolate levels in vegetative tissues. To investigate whether UV-B radiation could be used to enhance glucosinolate accumulation, we systematically examined the modulation of glucosinolate profiles and associated biosynthetic pathways in leaves of the ‘double-low’ cultivar NY4 under white light (WL) supplemented with two UV-B intensities: low-intensity UV-B (UVBL, 0.1 W m⁻²) and high-intensity UV-B (UVBH, 0.4 W m⁻²). Rapeseed seedlings were treated for 21 days under a 16 h photoperiod, and leaf samples were collected at the end of the treatment period, with three biological replicates per condition. Compared with the WL control, UVBL significantly increased total glucosinolate content by 64.57%, driven predominantly by elevated accumulation of progoitrin and neoglucobrassicin. In contrast, UVBH reduced total glucosinolate levels but markedly elevated gluconasturtiin content. Transcriptome analysis revealed that UVBL upregulated key genes involved in glucosinolate biosynthesis (e.g., MAM, IPMDH, CYP79F1, and SOT17/18) and transcription factors (e.g., MYB28, MYB34, MYB51, and MYB122). Conversely, UVBH downregulated genes associated with side-chain elongation of aliphatic glucosinolates and secondary modification of indolic glucosinolate. Collectively, these results demonstrate that low-intensity UV-B radiation can effectively boost total glucosinolate content in rapeseed leaves via transcriptional reprogramming.