Search Results (198)

Vegetables and fruits grown in urban areas pose a potential threat to human health due to contamination with heavy metals (HMs). This study aimed to identify and quantify the concentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Cd) in tomatoes, leafy vegetables, and fruits collected from 16 allotment gardens (AGs) located in Warsaw. A total of 112 samples were analyzed (72 vegetable and 40 fruit samples). Vegetables from AGs accumulated significantly higher levels of HMs than fruits. Leafy vegetables, particularly those cultivated near high-traffic roads, exhibited markedly elevated levels of Pb, Cd, and Zn compared to those grown in peripheral areas. Lead concentrations exceeded permissible limits by six to twelve times, cadmium by one to thirteen times, and zinc by 0.7 to 2.4 times. Due to high levels of Pb and Cd, tomatoes should not be cultivated in urban environments. Regardless of location, only trace amounts of HMs were detected in fruits. The greatest health risk is associated with the consumption of leafy vegetables. Lettuce should be considered an indicator plant for assessing environmental contamination. The obtained Hazard Index (HI) values indicate that only the tested fruits are safe for consumption. Meanwhile, the values of the Hazard Quotient (HQ) indicate no health risk associated with the consumption of lettuce, cherries, and red currants. Among the analyzed elements, Pb showed a higher potential health risk than other metals. This study emphasizes the need for continuous monitoring of HM levels in urban soils and the establishment of baseline values for public health purposes. Remediation of contaminated soils and the implementation of safer agricultural practices are recommended to reduce the exposure of urban populations to the risks associated with the consumption of contaminated produce. In addition, the safety of fruits and vegetables grown in urban areas is influenced by the location of the AGs and the level of industrialization of the agglomeration. Therefore, the safety assessment of plant products derived from AGs should be monitored on a continuous basis, especially in vegetables. Full article

Optimizing artificial lighting in controlled-environment agriculture is crucial for enhancing crop productivity and resource efficiency. This study presents a spectral–spatial co-optimization strategy for LED lighting tailored to the physiological needs of Italian lettuce (Lactuca sativa L. var. italica). A miniature plant factory system was developed with dimensions of 400 mm × 400 mm × 500 mm (L × W × H). Seven customized spectral treatments were created using 2835-packaged LEDs, incorporating various combinations of blue and violet LED chips with precisely controlled concentrations of red phosphor. The spectral configurations were aligned with the measured absorption peaks of Italian lettuce (450–470 nm and 640–670 nm), achieving a spectral mixing uniformity exceeding 99%, while the spatial light intensity uniformity surpassed 90%. To address spatial light heterogeneity, a particle swarm optimization (PSO) algorithm was employed to determine the optimal LED arrangement, which increased the photosynthetic photon flux density (PPFD) uniformity from 83% to 93%. The system operates with a fixture-level power consumption of only 75 W. Experimental evaluations across seven treatment groups demonstrated that the E-spectrum group—comprising two violet chips, one blue chip, and 0.21 g of red phosphor—achieved the highest agronomic performance. Compared to the A-spectrum group (three blue chips and 0.19 g of red phosphor), the E-spectrum group resulted in a 25% increase in fresh weight (90.0 g vs. 72.0 g), a 30% reduction in SPAD value (indicative of improved light-use efficiency), and compared with Group A, Group E exhibited significant improvements in plant morphological parameters, including a 7.05% increase in plant height (15.63 cm vs. 14.60 cm), a 25.64% increase in leaf width (6.37 cm vs. 5.07 cm), and a 6.35% increase in leaf length (10.22 cm vs. 9.61 cm). Furthermore, energy consumption was reduced from 9.2 kWh (Group A) to 7.3 kWh (Group E). These results demonstrate that integrating spectral customization with algorithmically optimized spatial distribution is an effective and scalable approach for enhancing both crop yield and energy efficiency in vertical farming systems. Full article

Environmental and health concerns have increased the demand for ready-to-eat vegetables rich in bioactive compounds. This study explores the impact of red and blue (R:B) LED light on the metabolic responses of lamb’s lettuce (Valerianella locusta L.), focusing on sugars, organic acids, total phenolics, antioxidant activity, and enzyme inhibition. Post-harvest analyses were also conducted to assess shelf-life and microbiological characteristics of the product. The R:B LED treatment significantly enhanced plant growth, with a 133% and 68% increase in shoot fresh and dry weights, respectively, and a 21% increase in leaf area compared to controls (white LED light). Biochemical profiling revealed substantial increases in fructose (255%), sucrose (169%), citric acid (350%), and malic acid (868%) under R:B LED light. Additionally, phenolic content increased by 30%, alongside a notable modulation of 258 secondary metabolites, including flavonoid glycosides, alkaloids, and terpenoids. These biochemical changes contributed to a marked improvement in antioxidant capacity (12–45% across multiple assays) and a 300% increase in α-glucosidase inhibition, suggesting potential antidiabetic properties. Furthermore, post-harvest analysis revealed comparable shelf-life and microbiological safety between R:B and white LED-grown samples. The research highlights the potential of LED light to enhance plant biochemical responses and improve crop quality without affecting post-harvest quality, paving the way for sustainable agricultural innovations. Full article

Indoor farming presents a sustainable response to urbanization and climate change, yet optimizing light use efficiency (LUE) remains vital for maximizing crop yield and minimizing energy use. This study introduces an IoT-based framework for adaptive light management in controlled environments, using lettuce (Lactuca sativa L.) as a model crop due to its rapid growth and sensitivity to light spectra. The system integrates advanced LED lighting, real-time sensors, and cloud-based analytics to enhance light distribution and automate adjustments based on growth stages. The key findings indicate a 20% increase in energy efficiency and a 15% improvement in lettuce growth compared to traditional static models. Novel metrics—Light Use Efficiency at Growth stage Canopy Level (LUEP) and Lamp Level (LUEL)—were developed to assess system performance comprehensively. Simulations identified optimal growth conditions, including a light intensity of 350–400 µmol/m²/s and photoperiods of 16–17 h/day. Spectral optimization showed that a balanced blue-red light mix benefits vegetative growth, while higher red content supports flowering. The framework’s feedback control ensures rapid (<2 s) and accurate (>97%) adjustments to environmental deviations, maintaining ideal conditions throughout growth stages. Comparative analysis confirms the adaptive system’s superiority over static models in responding to dynamic environmental conditions and improving performance metrics like LUEP and LUEL. Practical recommendations include stage-specific guidelines for light spectrum, intensity, and duration to enhance both energy efficiency and crop productivity. While tailored to lettuce, the modular system design allows for adaptation to a variety of leafy greens and other crops with species-specific calibration. This research demonstrates the potential of IoT-driven adaptive lighting systems to advance precision agriculture in indoor environments, offering scalable, energy-efficient solutions for sustainable food production. Full article

Aeroponic plant cultivation is a novel technology explored for its potential in indoor farming. In this study, we evaluated the effects of seed treatments with cold plasma on growth, physiological processes, and biochemical parameters in two lettuce cultivars—green variety ‘Perl Gem’ and red variety ‘Cervanek’ cultivated in an aeroponic system for 45 days. Seeds were treated with low-pressure air plasma for 3 min (further denoted as LCP3) or atmospheric dielectric barrier discharge (DBD plasma) for 3 and 5 min (referred to as DBD3 and DBD5 groups). We estimated the effects of seed treatments on parameters of seedling growth, photosynthetic efficiency, amounts of photosynthetic pigments, anthocyanins, total phenolic compounds (TPC), and antioxidant activity in leaves. Despite the observed effects on germination and early growth, seed treatments did not affect biomass gain or head/root ratio in both lettuce cultivars. Seed treatments increased the photosynthetic performance index and amounts of photosynthetic pigments in ‘Pearl Gem’ but not ‘Cervanek’ leaves. Seed treatments enhanced the content of protective phenolic compounds and antioxidant activity in ‘Pearl Gem’, and anthocyanin content in ‘Cervanek’ leaves, indicating potential to improve the nutritional value of the edible part of lettuce cultivated in an aeroponic system. Full article

As climate change destabilizes food crop production, there is a growing interest in controlled environment agriculture (CEA). Although light-emitting diodes (LED) have made CEA economically viable for some high-value crops when coupled to agrivoltaics (solar photovoltaics + agriculture), it has generally not been used for root vegetables. This is the first study to demonstrate that radishes and turnips could be grown in a reasonable period of eight weeks in an agrivoltaic agrotunnel using both lighting and grow walls optimized for lettuce growth. As reduction in LED energy use is important to minimize capital costs for solar energy, this study investigated three lighting treatments (red, white, and full-spectrum as control). The normalized yields (adjusted for total energy provided by each treatment) showed that both cultivars preferred red light, and harvested green leaves provided higher masses than the roots, although turnips appeared to be far more adaptable to vertical growth than radishes (>450% for roots and >50% for leaves per pot compared to radishes for the control treatment). The results show promise for providing true net-zero carbon emission root vegetables year-round with similar agrivoltaics-powered CEAs. Future work is needed with light intensity trials to optimize light recipes. Full article

The alterable light/dark cycle in a plant factory with artificial lighting eliminates the traditional concept of day and night in nature. Adjusting the light/dark cycle to closely align with the inherent circadian rhythm of plants can enhance biomass accumulation. In this study, we examined the effects of different light/dark cycles on the photosynthetic performance, growth, and energy use efficiency of two hydroponic lettuce cultivars (Lactuca sativa L. cv. ‘Frillice’ and ‘Crunchy’). The lettuces were subjected to four light/dark cycle treatments—16 h light/8 h dark (L₁₆D₈, as control), 12 h light/6 h dark (L₁₂D₆), 8 h light/4 h dark (L₈D₄), and 4 h light/2 h dark (L₄D₂), all under LED lamps with white combined red chips at the same light intensity of 250 μmol m⁻² s⁻¹. Photosynthetic performance and growth index were measured during the slow and rapid growth stages, corresponding to days 9 and 21 after transplanting, respectively. For Frillice, L₁₂D₆ achieved the highest shoot dry weight and light and electricity energy use efficiencies on days 9 and 21 after transplanting, primarily due to the largest leaf area, leaf number, and net photosynthetic rate. For Crunchy, L₁₂D₆ and L₈D₄ increased shoot fresh and dry weights due to larger leaf area and leaf number on day 9 after transplanting compared with L₁₆D₈. Subsequently, the lettuces in L₁₆D₈ exhibited a rapid increase in leaf area and leaf number, along with a high net photosynthetic rate during the rapid growth stage, resulting in fast shoot biomass accumulation. There were no significant differences in the shoot dry weight and energy use efficiency between L₁₆D₈ and L₁₂D₆ on day 21 after transplanting. Two lettuce cultivars in L₁₆D₈ both exhibited the highest water use efficiency on day 21 after transplanting. In conclusion, the light/dark cycle lighting can alter lettuce biomass accumulation by modifying plant morphology and leaf net photosynthetic rate. Additionally, the physiological response to the light/dark cycle was cultivar-dependent. Our findings provide valuable insights for optimizing hydroponic lettuce production to achieve high yield in LED plant factories. Full article

Light is crucial in controlled-environment agriculture (CEA), affecting germination, growth, and overall plant quality. Here, we explored the optimization of various LED light spectra on the germination traits such as germination percentage, mean germination time, germination index, vigor index, and early seedling growth of ‘Lollo Bionda’ lettuce seedlings in a plant factory. A completely randomized design was implemented, involving three replications. LED lamps with different spectral compositions—red (R, peak at 656 nm), red/blue (3:1 ratio, R:B, peak at 656 nm), blue (B, peak at 450 nm), and white (400–700 nm)—were utilized in this study. The combination of red and blue LED lights, along with monochromatic red and blue treatments, significantly enhanced germination traits and early seedling growth compared to white and ambient lighting. The combined spectrum resulted in the highest seedling emergence, the longest shoot and root lengths, and the highest fresh weight. These findings underscore the potential of the LED technology to improve germination efficiency and enhance seedling quality in CEA. Future studies should refine multispectral LED strategies by examining factors such as light intensity and photoperiod, while also elucidating the molecular pathways involved in light-driven germination and early development in lettuce. Full article

Lighting from light-emitting diodes (LEDs) is one of the largest capital and operational expenses for indoor farms. While broad-waveband white LEDs are relatively inexpensive, their efficacy is lower than most narrow-band LEDs. This study aimed to determine how supplementing warm-white light with additional blue (400–499 nm), green (500–599 nm), red (600–699 nm), or far-red (700–750 nm) light influences lettuce (Lactuca sativa) growth and quality, and whether these effects are consistent across two photon flux densities (PFDs). We grew lettuce ‘Rouxai’ and ‘Rex’ under 90 or 180 µmol∙m⁻²∙s⁻¹ of warm-white light supplemented with 40 or 80 µmol∙m⁻²∙s⁻¹ of blue, green, red, far-red, or warm-white light. Supplemental far-red light increased biomass without reducing secondary metabolites. Supplemental red, far-red, and warm-white light maximized biomass, whereas additional blue light enhanced secondary metabolite concentrations and leaf coloration. Increasing the PFD increased biomass and phenolic content in ‘Rouxai’. Notably, spectral effects were consistent across PFD levels, suggesting that higher PFDs do not diminish spectral responses. These results demonstrate the potential of enriching white light to increase yield or quality in controlled-environment agriculture and provide insights for cost-effective commercial production. Full article

Cultivated lettuce (Lactuca sativa L.) is considered one of the most important economic vegetables worldwide; however, it is subjected to different stresses (salt stress, etc.) during its growth and development, resulting in yield reductions. In this study, we selected cultivated red lettuce and wild lettuce species (Lactuca serriola L.) to investigate the phenotypic and physiological changes in these lettuce under different salt treatment conditions. Functional annotation and enrichment analysis of the differentially expressed genes (DEGs) in the lettuce leaves and roots between the control and salt treatments were performed, identifying the key genes responding to salt stress. The results showed that the growth of the two types of lettuce was limited by salt stress, with decreased leaf area, main root length, biomass, and photosynthesis parameters noted. The cultivated red lettuce and the wild lettuce exhibited similar trends in terms of the variation in their antioxidant enzymatic activity and the content of osmoregulatory compounds in their leaves. The results of our transcriptomic analysis revealed that the mitogen-activated protein kinase (MAPK) signaling pathway, transporters, cytochrome P450, phenylpropanoid biosynthesis, and isoflavonoid biosynthesis were involved in the response to salt stress in the lettuce seedlings. The red lettuce cultivar showed a greater abundance of DEGs related to secondary metabolite biosynthesis and aquaporins under the salt treatment, resulting in a salinity-tolerant capacity comparable to that of the wild lettuce species. These results reveal important biosynthesis pathways that may play a key role in the salt tolerance of lettuce seedlings and provide key candidate genes that could be functionally characterized further and utilized to genetically improve new salt-tolerant varieties. Full article

The use of biostimulants derived from protein hydrolysates (PH) is now recognized as an effective strategy to promote sustainable vegetable production. This study aimed to evaluate the effects of the foliar application of PH derived from hempseed press cakes on Red Oak lettuce cultivated under greenhouse conditions. Foliar applications of PH at concentrations ranging from 0% to 7.5% (w/v) were compared with water (control) and a commercial product (Germinate^®), applied weekly until 35 days after transplanting (DAT). Growth parameters, including plant height, plant width, leaf number, and leaf length and width, were recorded at 14 DAT and subsequently recorded weekly until harvest. Moreover, the fresh and dry weight, chlorophylls, mineral contents, antioxidants, and their activities in the harvested plants were determined. The results showed the positive effects of the hempseed press cake-derived PH on growth, yield, mineral contents, antioxidants, and antioxidant activities. In particular, the foliar application of PH at a concentration of 7.5% (w/v) is recommended to improve the yield and nutritional values in Red Oak lettuce. This study reports the first detailed research on the use of PH derived from hempseed press cakes for lettuce and may offer a sustainable alternative for vegetable production. Full article

Controlled-environment crop production often weakens plants’ defense mechanisms, reducing the accumulation of protective phytochemicals essential to human health. Our previous studies demonstrated that short-term supplementation of low-dose ultraviolet (UV) light to the red–green–blue (RGB) spectrum effectively boosts secondary metabolite (SM) synthesis and antioxidant capacity in lettuce. This study explored whether similar effects occur in basil cultivars by supplementing the RGB spectrum with ultraviolet B (UV-B, 311 nm) or ultraviolet C (UV-C, 254 nm) light shortly before harvest. Molecular analyses focused on UV-induced polyphenol synthesis, particularly chalcone synthase (CHS) level, and UV light perception via the UVR8 receptor. The impact of high-energy UV radiation on the photosynthetic apparatus (PA) was also monitored. The results showed that UV-B supplementation did not harm the PA, while UV-C significantly impaired photosynthesis and restricted plant growth and biomass accumulation. In green-leaf (Sweet Large, SL) basil, UV-B enhanced total antioxidant capacity (TAC), increasing polyphenolic secondary metabolites and ascorbic acid (AsA) levels. UV-C also stimulated phenolic compound accumulation in SL basil but had no positive effects in the purple-leaf (Dark Opal, DO) cultivar. Interestingly, while the UV-B treatment promoted UVR8 monomerization in both cultivars, the enhanced CHS level and concomitant SM synthesis were noted only for SL basil. In addition, UV-C also induced CHS activity and SM synthesis in SL basil but clearly in a UVR8-independeted manner. These findings underscore the potential of UV light supplementation for enhancing plant functional properties, highlighting species- and cultivar-specific effects without compromising photosynthetic performance. Full article

Leafy greens injuries occur from farm to table, causing leakage of cellular contents that promote the multiplication of foodborne pathogens and impose oxidative stress. Fresh beverages made from blended uncooked fruit and vegetables have become a popular food. The effect of cellular contents of different leafy greens on the multiplication of the important pathogen Escherichia coli O157:H7 (EcO157) under temperature abuse was investigated. Leafy greens consisted of spinach and different lettuce types (romaine, iceberg, butterhead, green leaf, and red leaf). Fructose, glucose, and sucrose concentrations in the leaves were quantified by HPLC. H₂O₂ concentration was measured via a peroxidase-based assay. Young leaves of iceberg, romaine, and green leaf lettuce held significantly greater total amounts of the three carbohydrates than middle-aged leaves. Except for iceberg and red leaf lettuce, all middle-aged leaves contained greater H₂O₂ than young leaves. EcO157 density change in leaf contents over 5 h incubation related neither to individual nor total carbohydrate concentration but was negatively associated with H₂O₂ concentration (regression analysis; p < 0.05). Given the common use of antioxidants to maintain the organoleptic aspects of homogenized produce beverages and certain fresh-cut produce, the antimicrobial effect of reactive oxygen species may be important to preserve in ensuring their microbial safety. Full article

Lettuce genetic transformation is genotype-dependent. In the present study, we have successfully developed an optimized Agrobacterium-mediated transformation protocol for elite lettuce cultivars, which belong to the romaine, leaf, and butterhead cultivar types. We optimized the type and concentration of plant growth regulators (PGRs) and selection antibiotics and found that the use of 1-naphthaleneacetic acid (NAA; 0.10 mg/L) and 6-benzyladenine (BA; 0.25 mg/L) as plant growth regulators, the use of hygromycin (15 mg/L) for transgenic plant selection, and the use of cotyledons and the first true leaf as explants efficiently yielded transformed plants for seven out of the eleven tested cultivars, achieving a 24.3–100% transformation efficiency. These seven cultivars include two romaine-type cultivars, three leaf-type cultivars, and two butterhead-type cultivars, and mark the first successful genetic transformation of the romaine cultivars ‘Kahu’ and ‘Rosalita’, the leaf cultivars ‘Red Sails’ and ‘Royal Oak Leaf’, and the butterhead cultivar ‘Lollo Biondo’. We also observed that substituting hygromycin selection with kanamycin selection (40 mg/L) resulted in a 64.3% transformation efficiency in the butterhead-type ‘Mariska’, one of the remaining four cultivars. Our newly optimized protocols are applicable in elite lettuce cultivars for Agrobacterium-mediated genetic transformation and regeneration, enabling hygromycin or kanamycin selection. Full article

The use of extended light spectra, including UV-A, green, and far-red, has been scarcely explored in vertical farming. This study evaluated the effects of full spectra under two intensities (90 and 180 µmol m⁻² s⁻¹) on the growth and antioxidant properties of green and purple leaf lettuce. Three light spectra were tested: Blue-White (BW), Red-White (RW), and Red-Blue (RB). Fresh weight (FW), dry weight percentage (DWP), chlorophyll concentration (NDVI), and antioxidant parameters (total phenolic content (TPC), antioxidant capacity by DPPH and FRAP and total flavonoid content (TFC)) were assessed. Spectrum-intensity interactions significantly influenced FW, with RW-180 µmol m⁻² s⁻¹ yielding the highest FW (78.2 g plant⁻¹ in green and 48.5 g plant⁻¹ in purple lettuce). BW-90 µmol m⁻² s⁻¹ maximized DWP in green lettuce, while PAR intensity of 180 µmol m⁻² s⁻¹ favored DWP in purple lettuce. Chlorophyll concentration increased under PAR intensity of 180 µmol m⁻² s⁻¹, and leaf color varied with spectrum, with RW producing lighter leaves. Antioxidant parameters declined over time, but a PAR intensity of 180 µmol m⁻² s⁻¹, particularly under RW, boosted TPC and TFC contents in both lettuce cultivars during early stages (days 0 and 15). Conversely, a lower PAR intensity of 90 µmol m⁻² s⁻¹, mainly under RW, enhanced antioxidant capacity by FRAP at 15 days and by the end of the cycle for both cultivars. Overall, RW-180 µmol m⁻² s⁻¹ interactions promoted the best characteristics in lettuce. Nonetheless, the findings emphasize the significance of fine-tuning both light spectrum and intensity to enhance lettuce growth and quality in vertical farming systems considering the cultivar, time and variable to be evaluated. Full article