Microgreens are quickly-grown greens that are suitable for urban areas. The accumulation of chlorophyll in plants is essential for both nutritional compounds and the microgreen’s attractive appearance. A plant factory is a controlled-environment cultivation method that employs LEDs to enhance photosynthesis, vegetative development, seed germination, and chlorophyll accumulation. This work used VIS-NIR for the quantitative determination of chlorophyll content in green and red spinach microgreens grown under four different LED light intensities with four different ratios, with 100% blue, red, and white LED, and 67%:20%:13% of red:blue: white LED, as artificial grow for 12 hours illumination. The performance of MSC, AN, SNV, smoothing, and the first and second Savitzky-Golay’s derivatives (SGD) were examined. PLSR explained accurately predicted R²C, R²P, RMSEC, and RMSEP up to 0.957, 0.892, 1.054, and 1.661 for chlorophyll a using SGD 1st; 0.813, 0.652, 0.979, and 1.338 for chlorophyll b using SNV; and 0.931, 0.876, 1.155, and 1.550 for total chlorophyll using SNV. The wavelength region of 400 to 700 nm was dominant based on the best regression coefficient (β) for predicting green and red spinach microgreens. Results demonstrated that VIS-NIR spectroscopy, combined with chemometric techniques, PLSR, can be used to evaluate the chlorophyll content of green and red spinach microgreens.

To meet global food demand, agricultural systems must enhance crop performance, productivity, and sustainability. Biostimulants have emerged as a promising strategy, particularly in vegetable production, due to their ability to enhance plant growth and resilience. This study characterized milk-derived protein hydrolysates (MPH) produced from expired milk and evaluated their potential as biostimulants for hydroponic cos lettuce. Hydrolysis of expired milk with hydrochloric acid achieved 94.55% hydrolysis and yielded 80.77% free amino acids. MPH was applied at volumes of 0, 1, 3, and 5 mL L⁻¹ in combination with Hoagland and Arnon nutrient solution. The 1 mL L⁻¹ (MPH1) treatment significantly increased shoot and root biomass and canopy size while reducing nitrate accumulation and enhancing total flavonoid and ascorbic acid content, as well as antioxidant capacity. HPLC analysis showed that MPH1 treatment promoted the accumulation of key metabolites, including vanillic acid, para-coumaric acid, salicylic acid, ferulic acid, gallic acid, syringic acid, quercetin, myricetin, and naringenin. MPH1 improved uptake of phosphorus, potassium, calcium, magnesium, and iron, contributing to mineral biofortification and nutritional quality. These results demonstrate that MPH at 1 mL L⁻¹ is an effective biostimulant, improving yield and quality while reducing nitrate levels in hydroponically grown cos lettuce, offering a sustainable solution for food waste valorization.

By controlling environmental conditions, indoor farming can increase plant growth, productivity, and harvest quality. An additional element that can enhance lettuce yield is the utilization of plant biostimulants. These substances can boost nutrient absorption efficiency, enhance resistance to environmental stresses, and foster positive impacts on plant growth and maturation. This study examined the impact of red and green romaine lettuce with different plant biostimulants (Viva^®, Megafol^®, Radifarm^®) added to AB mix on lettuce growth under white LED lighting on 30 days of cultivation. The MANOVA tests showed that different varieties of romaine lettuce and plant biostimulants substantially affected chlorophyll b, total chlorophyll, leaf number, leaf area, leaf weight, and root weight. A polynomial growth model was also obtained from height data collected during 30 days of planting, with an optimal R², RMSE, MAE, and MAPE reaching the optimal value of 0.9926; 0.50; 0.46; 1.72, respectively, for red lettuce with Viva^®, and 0.9930; 0.11; 0.29; 2.37, respectively, for green lettuce with Viva^®. In addition, Pearson Correlation analysis between each treatment indicated a positive and substantial correlation in various growth indices, up to 0.901.

Light-Emitting Diode (LED) improves photosynthesis, vegetative development, seed germination, and chlorophyll content in a controlled-environment plant cultivation system. This study used LEDs as artificial grow illumination with 4 four distinct ratios, 100% blue, 100% red, 100% white, 67%:20%:13% red:blue:white, for 12 hours. Microgreens were watered twice daily with 250 ppm of plant nutrients, using a commercial AB mix and liquid organic fertilizer. Different LED ratios have varied lux and Photosynthetic Photon Flux Density (PPFD), i.e. 100 lux and 44.26 mol·m⁻²·s⁻¹ PPFD for 100% blue; 600 lux and 20.32 mol·m⁻²·s⁻¹ PPFD for 100% red; 1000 lux and 95.92 mol·m⁻²·s⁻¹ PPFD for 100% white; 350 lux, and 37.33 mol·m⁻²·s⁻¹ for 67%:20%:13% red:blue:white; with maintained 25-27°C of temperature and 70-80% of relative humidity. The 100% white LED lamp with AB Mix as plant nutrient resulted in the best growth of red and green spinach microgreens, with height, leaf area, fresh weight, chlorophyll a, chlorophyll b, and total chlorophyll content of 2.98 cm, 1.32 cm², 0.14 gr, 19.05 mg/ L, 11.38 mg/L, 19.76 mg/L for green spinach and 3.01 cm, 0.91 cm², 0.08 g, 19.12 mg/L, 9.93 mg/L, 18.50 mg/L for red spinach.