Search Results (70)

Cultivation knowledge deficiencies limit the appreciation of microalgae-based nutrient solutions on hydroponic plants. This study compared Chlorella vulgaris implications for lettuce growth and the production of high-value components through the use of four different co-cultivation hydroponic scenarios. The results of 30-day co-cultivation of Chlorella vulgaris and lettuce demonstrated the significance of controls of pH (7.0–7.75) and green microalgal cell density (10⁷ cells/mL) to improve the qualities in lettuce leaf growth, root vigor, and nutrient yield from days 15 to 30 during the co-cultivation. Plant height increased by 19%, leaf area by 4%, root cortex thickness by 14% (p < 0.05), total chlorophyll content by 49%, soluble sugar content by 12%, and protein content by 6% through the adoption of 1.0 × 10⁷~1.6 × 10⁷ cells/mL of microalgal solution during hydroponic cultivation. Furthermore, the aerated hydroponic device benefits of co-cultivating high-concentration Chlorella vulgaris and lettuce resulted in a 1.0-time increase in vitamin C compared to the cultivation of low-concentration Chlorella vulgaris. This study highlights the benefits of the sustainable strategy of the microalgal cultivation technique used in the hydroponic systems for nutritious and healthy leafy vegetable growers, which is also emphasized for eco-friendly bioactive compound production. Full article

Developing sustainable strategies for natural resource management and conservation under shifting climatic scenarios is increasingly necessary due to exacerbated abiotic stresses, such as salinity. Under salt stress, several negative effects are observed in plants, particularly in leafy vegetables such as lettuce (Lactuca sativa L.). To mitigate the effects of saline stress from brackish water, several strategies have been adopted, including hydroponic cultivation. Therefore, this study aimed to determine the effects of variations in nutrient solution concentration and volume per lettuce plant cultivated in a nutrient film technique (NFT) hydroponic system using brackish water. The experiment was conducted using a randomized complete block design in a 2 × 2 × 2 factorial scheme, combining two levels of water electrical conductivity (ECw of 0.3 and 5.0 dS m⁻¹), two nutrient solution concentrations (NSC of 50 and 100%), and two nutrient solution volumes (NSV of 1 and 2 L plant⁻¹), with four replications. Growth, production, and water productivity variables were evaluated at 20 and 25 days following the imposition of treatments. The responses of the variables to saline stress varied according to the evaluation period (20 and 25 days), depending on the NSC and NSV levels. At the end of the 25-day cycle, it can be concluded that for lettuce cultivation using brackish water, the NSC can be reduced to 50% and provide an NSV of 2 L plant⁻¹. Under these growing conditions, leaf fresh matter production loss was approximately 40% lower than under cultivation without saline stress, which yielded 144.11 g plant⁻¹ under 100% NSC and an NSV of 2 L plant⁻¹. In contrast, water productivity of fresh matter was similar, at 78.68 and 76.55 g L⁻¹, respectively. Full article

In controlled-environment agriculture (CEA), light serves both as an energy source for photosynthesis and as a regulatory factor. However, the light responses of underutilized leafy greens are still not fully characterized compared with model crops such as lettuce. This study evaluated the effects of lighting parameters on the growth, metabolism, antioxidant properties, and mineral composition of Chrysanthemum coronarium (shungiku) greens cultivated hydroponically in CEA. Three parallel experiments were conducted, aiming to explore the effects of (I) light spectrum using red (R, 660 nm), blue (B, 447 nm), and combined RB light; (II) photoperiod, using 12, 16, and 24 h photoperiods at equal daily light integral; and 150, 200, 250, and 300 µmol m⁻² s⁻¹ photosynthetic photon flux density (PPFD) at 16 h photoperiod. RB light promoted the highest biomass accumulation and light use efficiency (LUE), while monochromatic red and blue light limited growth and reduced Fe and Zn contents. A 12 h photoperiod yielded the best results for leaf area, fresh weight, and LUE compared with 16 and 24 h photoperiods. Higher PPFD increased biomass, soluble sugars, antioxidant capacity, organic acids, and micronutrients, with peak LUE at 200 µmol m⁻² s⁻¹ instead of the maximum yield at 300 µmol m⁻² s⁻¹. These findings emphasize the importance of crop-specific and trait-oriented light optimization for underutilized leafy vegetables. Full article

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m⁻²·s⁻¹. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems. Full article

Excessive nitrate accumulation in leafy vegetables presents significant health risks, requiring sustainable strategies to optimize yield while minimizing nitrogen-related anti-nutritional factors in controlled environments. This study investigated the effects of varying LED light intensities 236.9 µmol·m⁻²·s⁻¹ (high), 189.8 µmol·m⁻²·s⁻¹ (medium), and 117.6 µmol·m⁻²·s⁻¹ (low) on nitrates (NO₃⁻) dynamics, growth, and biochemical composition in two Lollo Rossa lettuce cultivars, Carmesi and Carnelian, grown in NFT hydroponic systems. Conducted under constant temperature (20/18 °C day/night) and CO₂ (625 µmol·mol⁻¹) to isolate light’s influence, the experiment used a replicated design with three replicates per treatment, each including two cultivars. Morphological traits (plant height, rosette diameter, leaf number, biomass, root development) and biochemical parameters (nitrate and sugar contents) were assessed via mean comparisons, trends, and correlations. Results demonstrated that higher light intensity significantly suppressed nitrate accumulation in lettuce through enhanced assimilation and dilution effects linked to increased growth. Nitrate levels dropped to 2091.67 mg kg⁻¹ from 2443.33 mg kg⁻¹ in Carmesi and 2013.33 mg kg⁻¹ from 2515.00 mg kg⁻¹ in Carnelian. Negative correlations were observed between nitrate content and growth parameters: nitrates vs. fresh biomass (r = −0.89); nitrates vs. plant height (r = −0.79). Concurrently, it boosted carbohydrate content (Carmesi: 3.03 °Brix; Carnelian: 3.08 °Brix) and promoted vigorous growth, with Carmesi achieving superior metrics under high light (height: 22.12 cm, rosette diameter: 29.87 cm, fresh biomass: 206.88 g, root biomass: 19.58 g) compared to low light (17.45 cm height, 183.42 g biomass). Carnelian exhibited similar trends but prioritized root elongation. These findings underscore light’s role in regulating nitrate transporters and assimilation enzymes (e.g., nitrate reductase), offering a low-cost approach to reduce nitrate risks, enhance nutritional quality, and improve yield in controlled horticultural systems (CHS). Full article

Toxic Cd (cadmium) pollution in agricultural soil has been drawing global attention. Using exogenous regulators to detoxify Cd in crops is a promising approach to alleviate Cd stress and prevent Cd accumulation in human bodies through the food chain. Natural compounds show great potential due to their environmentally friendly properties. We have found that thymol (a plant-derived natural compound) protects plants from Cd stress. To extend the application of thymol in agriculture, further studies are needed to understand the detailed mechanism by which thymol induces Cd tolerance and limits Cd accumulation in crops. In this study, hydroponic experiments using the roots of Brassica rapa L. exposed to a nutrient solution containing Cd (3 µM) and thymol (15 µM) were conducted to investigate the mechanism of thymol-induced Cd tolerance. Pot experiments with different vegetables (B. rapa, water spinach, and pepper) growing in Cd-polluted soil (0.5 µM Cd) were carried out to investigate the role of foliar spraying of thymol (15 µM) in decreasing the Cd content in vegetables. In the hydroponic study, thymol enhanced the shoot fresh weight and root fresh weight of B. rapa by 313% and 125%, respectively, upon Cd exposure. Thymol detoxifies Cd-induced ROS accumulation by increasing the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in B. rapa by 8.9–33.6%, 12.9–31.6%, and 57.8–135%, respectively. The thymol-activated AsA-GSH (ascorbic acid-glutathione) cycle also contributed to the decrease in ROS level. Thymol also reduced the Cd content in the shoots and roots of B. rapa by 55.7% and 46.6%, respectively, which was associated with the modulation of the expression of a set of genes accounting for Cd accumulation and transport. In the pot study, foliar spraying of thymol significantly decreased the Cd content in various vegetables, including leafy vegetables (B. rapa and two water spinach varieties, with leaf Cd decreasing by 40.5–45.9%) and solanaceous fruits and vegetables (three pepper varieties, with fruit Cd decreasing by 26.9–35.8%), which was accompanied by a growth-promoting effect. The results from this study elucidate the multifaceted function of thymol in helping vegetables detoxify Cd and decrease Cd bioaccumulation, shedding new light on developing thymol as a potential plant regulator to safeguard agroproduct security in Cd-polluted environments. Full article

Human health is profoundly influenced by external factors, with stress being a primary contributor. In this context, the digestive system is particularly susceptible. The prevalence of diseases affecting the small intestine and colon is increasing. Consequently, insoluble plant fibers, such as cellulose and hemicellulose, play a crucial role in promoting intestinal transit and maintaining colon health. Lettuce is a widely consumed leafy vegetable with high nutritional value and has been intensively studied through hydroponic cultivation. This study aims to optimize the cultivation conditions and freeze-drying process of Lugano and Carmesi lettuce varieties (Lactuca sativa L.) by identifying the optimal growth conditions, freeze-drying duration, and sample surface area in order to achieve an optimal percentage of insoluble fibers. Carmesi and Lugano varieties were selected based on their contrasting growth characteristics and leaf morphology, allowing to assess whether treatments and processing conditions have consistent effects on different types of lettuce. The optimal freeze-drying parameters were determined to include a 48 h freeze-drying period, a maximum sample surface area of 144 cm², and growth under combined conditions of supplementary oxygenation and LED light exposure. The optimal fiber composition, cellulose (21.61%), hemicellulose (11.84%) and lignin (1.36%), was found for the Lugano variety, which exhibited lower lignin and higher cellulose contents than the Carmesi variety. The quantification of hemicellulose, cellulose and lignin was performed using the well-known NDF, ADF and ADL methods. Therefore, optimized freeze-dried lettuce powder, particularly from the Lugano variety, presents a high-value functional ingredient for enriching foods and developing nutritional supplements aimed at digestive health. Full article

Hydroponic leafy vegetables have high yields, but their mechanized harvesting level is low. To improve the quality of orderly harvesting of hydroponic leafy vegetables, an ordered harvesting device with functions such as root flicking, posture adjustment and differential steering has been designed. A root-flicking method using rotating brushes was proposed, and experiments analyzed the effect of brush rotation direction. A posture adjustment method using a twisting conveyor belt was proposed, and experiments analyzed the impact of different twist angles on the stability of the adjustment process and the posture angle. A differential steering method using two pairs of conveyor belts with differential speeds was proposed, and experiments analyzed the impact of different steering belt speeds on steering stability and actual inclination angle. The root-flicking experiment results for hydroponic leafy vegetables showed that the counterclockwise followed by clockwise brush rotation combination performed better, with a root removal rate of 74.9%. The posture adjustment experiments on hydroponic leafy vegetables showed that the optimal twist angle for clamped and twisted conveyance was 35°, and the Mean Absolute Error (MAE) between the twist angle and hydroponic leafy vegetables posture angle was 0.38°. The differential steering experiment results indicated that the preferable belt speed difference for the directional conveyance of hydroponic leafy vegetables was 75 mm/s, and the MAE between the theoretical and actual inclination angles was 0.96°. Validation experiments based on posture adjustment and differential steering tests demonstrated a continuous harvesting success rate of 87.5%. This study provides valuable references for the design and development of orderly harvesting equipment for hydroponic leafy vegetables. Full article

Large-scale wireless sensor networks with electric field energy harvesters (EFEHs) offer self-powered, eco-friendly, and scalable crop monitoring in hydroponic greenhouses. However, their practical adoption is limited by the low power density of current EFEHs, which restricts the reliable operation of external sensors. To address this challenge, this work presents a noninvasive EFEH assembled with hydroponic leafy vegetables that harvests electric field energy and estimates plant functional traits directly from the electrical response. The device operates through electrostatic induction produced by an external alternating electric field, which induces surface charge redistribution on the leaf. These charges are conducted through an external load, generating an AC voltage whose amplitude depends on the dielectric properties of the leaf. A low-voltage prototype was designed, built, and evaluated under controlled electric field conditions. Two representative species, Beta vulgaris (chard) and Lactuca sativa (lettuce), were electrically characterized by measuring the open-circuit voltage (VOC) and short-circuit current (ISC) of EFEHs. Three regression models were developed to determine the relationship between foliar moisture content (FMC) and fresh mass with electrical parameters. Empirical results disclose that the plant functional traits are critical predictors of the electrical output of EFEHs, achieving coefficients of determination of $R^2=0.697$ and $R^2=0.794$ for each species, respectively. These findings demonstrate that EFEHs can serve as self-powered, noninvasive indicators of plant physiological state in living leafy vegetable crops. Full article

Watercress is a nutrient-dense, aquatic leafy vegetable with significant public health and economic potential. Hydroponically cultivated watercress can offer greater nutritional benefits due to the controlled delivery of specific nutrients. From an agronomist’s perspective, watercress has the advantage of optimized environmental resource efficiency, achieved through reduced energy, chemical, and water consumption, as well as its short cultivation cycle. Glucosinolates (GSLs) in watercress enhance sustainable agriculture by naturally protecting crops from pests and diseases, reducing the need for chemical inputs. They also increase market value and shelf-life, supporting resource-efficient and profitable farming. Within the pharmaceutical space, GSLs are well-known for their chemo preventive and anti-inflammatory properties. This review aims to summarize research findings, critically evaluate existing studies to highlight current knowledge, and identify research gaps, and to guide future investigations. The synthesis of the reviewed literature demonstrates that increased sulphate generally improves GSL content. However, not many studies have looked specifically at how magnesium sulphate (MgSO₄) affects watercress. This review highlights the specific impact of MgSO₄ on GSL production in watercress, which could provide valuable insights for optimizing nutrient management in hydroponic systems and enhancing the health benefits of this nutrient-dense crop. Full article

In controlled environment agriculture (CEA), CO₂ enrichment can promote photosynthesis while simultaneously reducing evapotranspiration, but the optimal settings vary depending on crop type, growth stage, and microclimate. This study presents a near-field remote sensing framework that fuses RGB image features with environmental variables to predict the CO₂ uptake/respiration dynamics of five leafy vegetables grown in a hydroponic culture system and evaluate their impact on resource efficiency under CO₂ control. A hybrid deep model incorporating You Only Look Once version 11 (YOLOv11) and a Residual Network with 50 layers (ResNet50) extracts growth-related visual cues and integrates them with tabular features (CO₂, temperature, and light conditions) to predict chamber CO₂ dynamics. Performance was evaluated by Mean Absolute Error (MAE)/Mean Squared Error (MSE) on withheld data, and the system-level impacts on water use (ET), pumping energy, and relative yield were analyzed using a conventional greenhouse model. The model exhibited high accuracy (MAE = 0.95; MSE = 1.62). Scenario analysis results showed that increasing ambient CO₂ concentration from 400 to 1200 ppm reduced modeled water demand by approximately 11%, increased modeled yield by approximately 9%, and resulted in a corresponding reduction in pumping energy per unit area. Unlike conventional single-crop, table-based approaches, this study demonstrates multi-crop generalization and image-environment fusion for CO₂ dynamic prediction, establishing proximity sensing as a viable decision-making layer for CEA. While yield/ET results were simulated rather than measured in long-term trials, and leaf area normalization was not available, the proposed framework provides a viable path for data-driven CO₂ control in indoor farms by linking image-based monitoring with operational optimization. Full article

The agricultural sector faces significant challenges related to climate change and population growth, which intensify pressure on natural resources and food security. Sustainable resource-efficient systems, alongside wastewater valorisation, are a promising solution. This study evaluated the reuse potential of aquaculture, urban, and swine farm wastewater in hydroponic cultivation. Trials with leafy vegetables and fruit crops were conducted in aquaponic systems containing two fish species (Koi carp and African catfish) and two small-scale hydroponic systems. Water quality, plant development, and environmental parameters were monitored. Results for the best performance scenarios within each cultivation system showed that in urban wastewater, strawberries yielded 183 ± 74 g/plant, exceeding yields in aquaponics (125 ± 60 g/plant). Lettuce performed better in swine farm wastewater (180 ± 39 g/plant) than in urban (65 ± 6 g/plant), with corresponding water-use efficiencies of 117 and 65 g/L. Aquaponics also supported stable yields, up to 108 ± 1 g/plant for lamb’s lettuce and 10,047 ± 8791 g of papaya fruit per plant. Nutrient recovery in hydroponic systems supplied with urban and swine farm wastewater reached up to 95% for N, P, and K. Overall, these systems demonstrated substantially lower water consumption compared with values commonly reported for conventional agriculture, underscoring their strong sustainability advantages. Full article

Resource efficiency is essential in today’s approach to horticulture. The global problems of water scarcity, soil pollution, biodiversity loss, and rapid growth of the global population require increased food production with fewer resources. Resource efficiency is an indicator that allows defining how much biomass an agri-food system can produce per unit of the resource used. Closed hydroponic systems, such as vertical hydroponic towers (VHTs), exhibit high resource efficiency. In these systems, the water use efficiency (WUE) and the nutrient use efficiency (NUE) can be calculated in terms of the water loss through transpiration and the ion concentration in the nutrient solution. The research aimed to determine the WUE and NUE for chard crops in VHT under greenhouse conditions and to evaluate its feasibility as an urban and peri-urban system for leafy vegetable production. Trials were carried out with chard in the fall 2024 in a tunnel-type greenhouse at the facilities of the Autonomous University of San Luis Potosi. The VHTs were built with a 20 L square lower deposit on which a cylindrical pipeline of 11.5 cm in diameter and 1.6 m in height was vertically placed. Each pipe had 45 growing containers distributed on 15 levels of three containers spaced vertically 9 cm and a density of 25 plants·m⁻². The experimental design was completely randomized with three treatments (75, 100, and 125% of Steiner’s nutrient solution) and three replications. The transpiration (Tr) of the crop (recording weight loss in the deposit) and the shoot fresh weight (SFW) of the plants were measured daily using a scale. An ANOVA and Tukey’s test for mean differentiation were performed with p < 0.05. Significant differences were found between treatments for SFW, WUE and NUE obtaining the best results at 75% of Steiner’s nutrient solution. Results show that WUE increased between 3 and 6 times, and NUE between 3 and 12 times compared to chard grown in soil. These results were equal and even higher than horizontal hydroponic systems or vertical farms. Vertical hydroponic closed towers installed in greenhouses are an optimal horticultural production system with high resources use efficiency. The implementation of VHT is feasible in areas where there is water scarcity or have a high population density. Full article

Dissolved oxygen (DO) concentration in nutrient solution is critical for maximizing yield and optimizing quality traits of lettuce plants grown in floating systems. This study evaluated the effects of two aeration systems—a Venturi system (V) and a Venturi system combined with a nanobubble generator using electromagnetic waves (VN)—compared with a non-aerated control (C), on quali-quantitative traits of lettuce plants grown in a floating system over two consecutive harvests. Both aeration treatments significantly increased DO levels in the nutrient solution compared to C, with the VN treatment maintaining the highest value throughout the crop cycle. Although no significant differences in lettuce yield were observed, both aeration treatments enhanced the leaf concentration of P, Mn, Zn, and Cu in the second harvest, and Mg in both harvests. Moreover, the VN treatment lowered leaf nitrate concentration in both harvests compared to the other treatments. The increase in DO in the nutrient solution delayed leaf senescence, as evidenced by higher chlorophyll index and lower anthocyanin levels in the lettuce leaves harvested at the end of the trial for both aeration systems. These results suggest that aeration, particularly with nanobubbles, can be an effective and sustainable strategy to enhance the quality traits of lettuce grown in a floating system. Full article

Underutilized leafy greens are considered as functional plant species primarily due to their resilience to abiotic stress factors, low nutrient requirements, and high nutritional value. Over the past 30 years, many experiments have been conducted to identify nutrient-efficient species, cultivars, landraces, and ecotypes, but few have successfully entered mainstream agriculture. The integration of these species into advanced horticultural systems, such as hydroponics, has the potential to further strengthen their impact on sustainable agriculture by minimizing use of resources, enabling year-round cultivation, and improving the nutritional profile of the harvested produce. As leafy vegetables, a primary food safety concern is the accumulation of nitrates in the leaves. In hydroponics, this issue is usually addressed by balancing the NH₄-N/total-N ratio (N_r) in the nutrient solution. Provided that the plant responses to high ammonia supply are species-dependent, three wild leafy greens, iceplant, corn salad, and common purslane, were grown in a soilless culture, with perlite as the substrate, under low (0.04) and high (0.12) N_r on a molar basis. Additionally, the potential of protein hydrolysates (PH) and seaweed extracts (SW) to alleviate plant tolerance to excess ammonia supply was also investigated. In terms of yield, high N_r led to significant yield restrictions in iceplant that reached 28%, while on corn salad, it had a positive impact, with yield increasing by 18%. Both biostimulant applications enhanced iceplant productivity only under optimal N_r conditions (0.04). Apart from yield responses, biofertilizers had no substantial impact on the plant nutrient profile. In contrast, high N_r suppressed nitrate accumulation in fresh leaves, while enhancing micronutrient uptake in all three plant species. In conclusion, this study highlights the pivotal role of biostimulants as plant stress protectors and growth regulators and identifies the optimal N_r ratio for maximizing the yield and quality performance of corn salad, iceplant, and common purslane in soilless cultivation systems. Full article